Frenchman Arnaud Clement, a former top 10 player on the ATP circuit, has revealed he was offered money to throw a tennis match.
"It happened to me but I will not tell you where or how," he said after his first-round defeat to Mikhail Youzhny at the Paris Masters Monday.
"I didn't hesitate for a second, I said no," added the 29-year-old, now ranked 53rd in the world.
"It may be different for a guy who's not that high up in the rankings and who has financial problems."
Clement, runner-up at the 2001 Australian Open, added: "It's very serious. I can't imagine that a top 10 player could accept that but it's hard to imagine as well that guys go to tournaments to make such offers.
"I haven't heard many players say it happened to them."
Earlier Monday French Tennis Federation (FFT) president Christian Bimes said organisers of the Paris event were taking the threat of possible match-fixing very seriously.
"We consider this a serious problem," Bimes said. "It is a dreadful disease which is a threat for tennis worldwide.
"We have to act straight away and be as severe with this as we are with doping," he added.
Betting on matches at the Paris event is being watched for anything suspicious, while matches are also being recorded and analysed by former players and ATP supervisors.
Players are also banned from betting at the venue.
Britain's Andy Murray claimed earlier this month that "everyone knows" corruption goes on in tennis.
His comments came after British online betting exchange Betfair suspended payouts because of unusual betting patterns after the August meeting between Russia's Nikolay Davydenko and lowly-ranked Argentine Martin Vassallo Arguello.
Davydenko, who has strenuously denied any wrongdoing, was fined $2,000 for not trying hard enough during his defeat by Marin Cilic at the St Petersburg Open last week.