London:British number one Andy Murray says "everyone knows" that match-fixing takes place on the professional tennis circuit.
Several players have revealed recently that they have been offered money to throw matches as the sport's governing body ATP investigates irregular betting activity.
And the 20-year-old says he is not surprised at the latest developments.
Murray, who is now 18 in ATP rankings, fears the temptation to cheat is too great for players who struggle to make a living in the professional game.
"It doesn't really surprise me," he told BBC Radio. "Some guys have to come to tournaments like this every single week and the first-round loser's cheque is sort of 2,500 euros and they have got to pay for their air fares and, you know, it's only a 10 or 12-year career so you have to make all your money while you're still playing."
The Scot feels the nature of the sport makes it difficult to prove when someone is trying to engineer an outcome.
"It's not really acceptable, it's difficult to prove if someone has tanked a match or not tried because they can try their best until the last couple of games of each set and then make some mistakes, a couple of double faults, and that's it," he added.
"It's pretty disappointing for all the players but everyone knows it goes on."
ATP has a zero tolerance policy towards players involved in gambling. They are investigating betting patterns concerning a match in Poland between Nikolay Davydenko and Martin Vassallo Arguello.
Russian Davydenko won the first set but later pulled out of the match due to injury. He has denied any wrongdoing.