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How To Fix a Tennis Match (by Boy Westerhof and Antal van der Duim)

Meerbusch is a small town in the west of Germany with a population of just over 50,000 residents. Since last year, it is also the host of the Maserati Challenger tennis tournament. As a tournament, they would have hoped to garner some attention, but they would never have expected to be the focus of attention of many hundreds of tennis fans on Twitter for around an hour and a half on Monday afternoon.

One would imagine that Boy Westerhof and Antal van der Duim also did not expect many people to be paying any attention to their match. The only one of the five singles matches being played today on a non-televised court, they would have expected nobody to be watching. Unfortunately for them, someone is always watching.

The match was first brought to my attention just after midday by Nick Spurett on Twitter, who had noticed that the price on Antal van der Duim had crashed in the preceding half hour.
Indeed, as we can see from Oddsportal, between 11:05 and 11:36, the price on Antal van der Duim on Pinnacle had collapsed from 2.70 into 1.83, at which point Pinnacle decided to suspend their market on the match. Marathon decided to keep their market open and we can see that their price was forced all the way into 1.20. A huge price move on any match. Checking Betfair, the price crash was quite clear.
Suspicious, but nothing particularly conclusive there. However, looking in slightly more depth revealed some more interesting observations. If we accept the Betfair price of 1.33 as being the correct price for the match, we would roughly expect van der Duim to be around 2.0-2.1 to win in straight sets and around 4.0 to win 2-1. Looking at the set betting for this match showed something far different.
The two correct scores for Antal van der Duim appear to be the wrong way around. For those that are unfamiliar with betting, the price of 1.95 on the van der Duim 2-1 scoreline equates to a probability of 51.3%. There is no possible situation where the price for a player to win 2-1 should be this short a price and certainly not based on the match prices.

The prices on Antal van der Duim and the 2-1 correct score continued to drop as the start of the match approached. Whether this was suspicious money or people simply following into the market on what they felt was a fixed match is not clear, but either way, the money kept coming.
There are several things to note here. The first is the amount of money matched on the markets. There is already over £40,000 match on the match winner market. No other match from Meerbusch had more than £5,000 matched at this point. As a comparison, tonight's match between Gilles Simon and Bernard Tomic, which is scheduled to start in just over three hours, currently has just under £20,000 matched on it.

As we can see, the odds on Antal van der Duim to win the match have not changed from the previous screenshot, but the price on the 2-1 scoreline has continued to crash, now trading at 1.58 or a 63.3% implied probability. Naturally, if the fix is for the 2-1 scoreline, the two players would have to split the first two sets to reach a deciding third set.

Based on the markets for the 1st Set Winner and the 2nd Set Winner, we can see what the script for the match is. Despite apparently having only a 25% chance of winning the match, Boy Westerhof is priced at having a 60.2% chance of winning the opening set. One might think this is rather peculiar. One would be correct. The favourite for the match should always be the favourite for the first set in the match.

The match started without too much incident. It was slightly peculiar that van der Duim shortened slightly after the first game where Boy Westerhof held serve, but it was only a small movement. The strange thing as the set progressed though was that whatever happened, the odds on the two players were stubbornly sticking at their pre-match level.

After nine consecutive holds, Antal van der Duim was serving to stay in the set at *4-5. If the script, as implied by the pre-match markets, was correct, he had to lose the opening set. He immediately dropped the opening three points of his service game to go *0-40 down. At this point, the market moved slightly.
Antal van der Duim's odds had drifted to 1.49 at this point. However, even if we did not change any of the pre-match service predictions, we would expect to see him around the 1.9-2.0 price if he were to lose the set. So, clearly he is still far too short. Despite winning two points, he dropped his serve and, with it, the first set. The market still had no worries about him coming back to win though.
In fact, his price had actually shortened again, despite losing the first set. At this point, the market is suggesting that he has a 71.9% chance of winning the match from a set down. Impressive given that he only had a 75.7% chance of winning the match at the start. In other words, losing the first set has made no difference to his chance of winning the match. It is almost as though someone knew what was going to happen.

Another easy hold at the start of the 2nd set for Boy Westerhof continued his excellent serving performance. He had dropped just six points in his first six service games. When he broke Antal van der Duim to make it *2-0 in the 2nd set, then held serve comfortably again, some might have thought that the fix was just a myth. Given the starting prices, Westerhof should have been priced around 1.40 at the biggest at this point. However, this was not quite the case.
Despite being 6-4, 3-0* down against a player ranked higher than himself, who had been serving excellently all match, it was still priced at van der Duim having a 64.1% chance of winning the match. In other words, despite being 3-0* down in the set, the chances of a van der Duim win had dropped just 7.8%. Frankly, this is just wrong - it would be very rare, even in a match involving the likes of Djokovic or Nadal against much lower ranked opposition, for a player to be this short a price at a set and a break down.

In his next service game, van der Duim was able to hold serve and get himself on the scoreboard in the 2nd set. At this point, the odds for the winner of the second set were rather interesting.
Despite being *3-1 up with a break of serve in the set, Boy Westerhof was priced at just 33.3% to win the set. Amazingly, Antal van der Duim was significantly shorter down a break in the set than he was before the match.

Boy Westerhof would not win another game in the set. From *30-30 in his next service game, his game would seemingly disintegrate. Van der Duim would break back, convincing the market that there was no concern.
Indeed, with the break back to make it 3-2*, Antal van der Duim would hit his lowest price to date at 1.21. His price would never look back. A hold of serve to make it 3-3 and the market was entirely convinced where this match was heading. When Westerhof was broken for a second consecutive game, the market was done.
After a run of 14 consecutive points, Westerhof finally won a point, but another break of serve and the second set was van der Duim's.
At the end of the second set, one might have expected to see the prices similar to those at the start of the match, probably with the favourite being slightly bigger, reflecting the fact that the match had become a one-set shootout.

One probably wouldn't have expected Antal van der Duim to have a 97.1% chance of winning the match. Except that everyone following the match did. Seven straight holds to 4-3* followed before the coup de grâce from van der Duim. A break to 30 and he would have the chance to serve for the match and to complete the fix.
Despite tempting people with a couple of break points, he eventually closed out the match. By this point, close to half a million pounds had been matched on the match market - well over twenty times the amount that would normally have been traded on this match.

As the initial markets had implied, Boy Westerhof would win the opening set of the match, then Antal van der Duim would launch a comeback to win the match in three sets. People would have looked at the 3-6, 6-4, 6-4 scoreline and not seen anything untoward. If the peculiarities had not been noticed before the match started, it may well have gone unnoticed for the whole match. It was an non-televised match from an obscure Challenger event in Germany - why would anyone be paying attention? Well, plenty of Twitter tennis fans had taken notice and had figured out precisely what had happened.

It is not the first time that either of these players have been involved in suspicious looking matches and it is time that the ATP, the ITF and the TIU started to do something about it. I have no doubt that this match was fixed by both players, who are close friends. Indeed, they are playing doubles together in this tournament. By losing in the first round, Boy Westerhof picked up a cheque for around $500. If Antal van der Duim loses in the next round against the top seed, Albert Ramos, he will collect around $800. By colluding on this match, they could have potentially picked up a windfall that would dwarf that prize money.

However, the chances are that nothing will be done and Challenger players will see that they can fix matches like this without punishment. I cannot prove 100% that this match was fixed - maybe the authorities could or maybe their tracks will be well-covered. However, based on the betting markets, there is little doubt for the vast majority of people that followed the match that it was blatantly and disgracefully fixed.

Only four players have ever been banned for life for fixing tennis matches - Daniel Koellerer, David Savic, Sergei Krotiouk and Andrey Kumantsov. They are clearly not the only three players involved in fixing in tennis. If the authorities do not even look into this match and take action, they are virtually giving players carte blanche to fix whatever matches and scorelines they fancy to supplement their income.

If no action or investigation is launched, many fans will lose what little faith remains in the authorities to combat the growing spectre of match-fixing in the sport. For the ATP and the TIU, the ball is now in their court. Do they have a response?


I have just been sent a link to an interview with Antal van der Duim after the match in a Dutch newspaper regarding the suspicions surrounding his match. He explains:
We play against each other so often. We haven't been approached before the game. Do I understand the accusations? People on twitter say so much, mainly cursing. Gamblers are frustrated losing money. I play to get higher on the ranking charts, not to make money. I haven't been on the challenger circuit that long. *
I do agree that far too many matches are called out as fixes on Twitter by gamblers that have lost money on matches that they felt was a certain thing. However, I do feel that in this case, the accusations are far more than the normal angry gamblers. Many people, including myself, that have not had any money on this match have flagged it up and the market movements were hugely suspicious. Was it fixed? I believe so, but it is up to the authorities to investigate it properly and make the final decision.

*Thanks to Michiel Jongsma (@JongsmaJongsma) for the translation


There are some comments from the Dutch tennis association in an article here where they state that:
"It is often very annoying for those guys, who are conscious of no harm. Their phones are buzzing now. We try to support the boys in their communication."
Regarding the investigation by the TIU, to whom the match has been reported by several sources, including the Dutch tennis association, they explain that:
"There may be days or weeks over it. They have a standard where they include analyzing betting patterns, but also to interview them." *
For now, the match has been reported to the TIU, which is as far as we can take it. From here, we are unlikely to hear anything, given that the TIU are notoriously secretive and only ever issue press releases announcing 'the outcome of an investigation that results in disciplinary action being taken.'

So, we may read a brief press release at some stage in the future, but the chances are that this is the last we will hear on this match. Fingers crossed that it is not, but as with many fans, there is little faith in the TIU given a seeming lack of any progress in the past few years.

* Thanks to DutchTennis (@DutchTennisTips) for the translation


  1. Great that someone takes this match up! It was a disgrase to bet on, only to realize the reality, when Duim breaked back to 2-3 in second set! Not being able to sell without a massive loss.
    Really hope theese players and event will be investegated further!

  2. gambling on tennis matches in such events is ridiculous anyway. if you don't want this to happen, you should ban gambling on challenger and future level.

  3. Imagine you make a lousy € 500 prize money a month, you invest the best years of your life trying to improve your game, are not very successful; and then... phone rings.... message: you will get an envelope with € 10.000 under your door in your hotel, just by losing a low profile match. Nothing peculiar, you loose all the time :)
    What would you do?

    1. I have written before about the temptation to fix matches at the lower levels of tennis, linking it in particular with the lack of money at those levels. Despite those temptations though, fixing a match for profit is still not something that can be condoned under any circumstances...

    2. Have you got an email address or a Twitter name through which I could contact you? I am researching this area and would like to know more.

    3. I dont understand why ITF ban Guillermo olaso for 5 years and dont han this players

  4. Well, what to say? People seem to be projecting their own low moral standards onto others. Since when is losing a match from a seemingly good position 'match fixing'? In this case it was only a set and a break (or two, I don't remember) which is not at all hopeless. It happens all the time that the player who is behind relaxed and starts to play better, where the one in front feels safe and loses his focus a little and suddenly the match changes. Roger Federer was at Wimbledon on the Brink of losing the final in 4 sets and had he been the one to serve first in the 5th he might even have won. Would we have said that Novak sold the match? Of course not.
    Those betters are looking at figures, not at real life tennis and they totally miss what the sport is about. Sadly enough for the players they are accusing of foul play the insinuations alone make people suspicious. Very hard to defend yourself against those bad thinkers. Start playing and stop betting! Much healthier for both body AND mind!

    1. If you read the article it has nothing to do with the outcome of the game! Or the turn around in second set. That happens all the time.

      It has to do with Van Der Duim remains a huge favorite even after being down 0-3 in second set.

      Odds on Van der Duim to win 2-1 in sets are lower than winning 2-0 in set.

      I haven't seen a more clear fix i my life

    2. You have rather missed the point of the article. Yes, players lose matches from leading positions all the time - that is not what is suspicious about this match. Rather it is how the markets reacted at all the positions during the match that is suspicious - the markets knew exactly what was going to happen in the match from before it even started. That is the problem.

      Of course making accusations of fixing against players make people suspicious about those players. That is why, unlike many people, I would never make an accusation such as this without strong evidence, albeit circumstantial, to back it up. The match is now being investigated by the TIU - the players will have their opportunity to defend themselves there against whatever evidence the TIU deems is relevant to the case...

    3. Check in some of the pasts games of Westerhof, he always wins at the beginning of the match and almost at the end of it, he has problems to score. So stop talking bullshit!

    4. I personally know both players and none of them would ruin their careers for money, as simple as that!

    5. Again - you Miss the point. It is about how people bet on this game. Not the match itself. Something is totally wrong here - even without players knowing this.

    6. To the guy defending Westerhof for losing matches from winning positions, actually he is 80% in his career for winning the match after winning the first set, that's pretty average for a male player and his 9-3 record in 2014 would also suggest he doesn't have a huge problem in this respect...

    7. Translations Dutch-English are bad.

      "Daar gaan soms dagen of weken overheen. Ze hebben een standaardprocedure waarbij ze onder meer gokpatronen analyseren, maar willen die jongens ook interviewen."
      Bad: "There may be days or weeks over it. They have a standard where they include analyzing betting patterns, but also to interview them." *
      Better: It may take days or weeks. They use a standard procedure to analyze betting patterns. They also want to interview both players.

      Het is vaak heel vervelend voor die jongens, die zich van geen kwaad bewust zijn. Ze worden nu helemaal platgebeld. Wij proberen die jongens onder meer in de communicatie te ondersteunen"
      Bad: "It is often very annoying for those guys, who are conscious of no harm. Their phones are buzzing now. We try to support the boys in their communication."
      Better: It's very annoying for those guys, who are not aware of having done wrong. Their phones are buzzing now. We try to support the men in their communication.

  5. Good and clear article, thanks!

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