Top seed Nikolay Davydenko received a warning from the umpire for not trying hard enough as he lost to Croatian qualifier Marin Cilic 1-6, 7-5, 6-1 in the second round of the St Petersburg Open.
The Russian played near flawless tennis in the first set but then started making numerous errors and committed 10 double-faults in the last two sets on Thursday.
He was then warned by Belgian umpire Jean-Philippe Dercq in the final set for tanking.
"I double-faulted to lose a game in the third set and he gave me a warning saying I was trying to lose on purpose," the world number four, whose match against Argentine Martin Vassallo Arguello in August is being investigated by the ATP Tour after irregular betting patterns, told reporters.
"I was simply shocked to hear him say that. This is just outrageous. How does he know what I was trying to do? I was so upset with the whole thing I started crying," added Davydenko, who was talking to the tournament supervisor after the match.
"Well, I was just trying to find out if they were going to fine me or not," he said.
"The reality is that I started feeling tired. My legs were just dead by the third set. Maybe my problems are psychological, maybe it's in my head."
He was cruising to a comfortable win after taking the first set in 27 minutes, but the 102nd-ranked Cilic broke him late in the second to level the score before racing through the decider to record a memorable victory.
CILIC SURPRISED
Cilic, 19, who also beat Davydenko in their only previous encounter at last month's China Open in Beijing, said he was a bit surprised by the manner of his victory.
"It was very tough for me to compete with him in the first set. He was hitting winners from almost anywhere, making no mistakes, but then he lost his concentration a little bit," said the Croat, who will take on fellow 19-year-old, Latvia's Ernests Gulbis, in Friday's quarter-finals.
"I don't think that he was not trying. Maybe he just lost his game plan and I took advantage of that."
Britain's second seed Andy Murray overcame Czech qualifier Lukas Dlouhy 6-2, 6-4 in the last match on centre court to reach the last eight, where he will face Russian fifth seed Dmitry Tursunov.
The 20-year-old Scot, who earlier this month said that match-fixing has been a common practice on the ATP Tour, said he was surprised by Davydenko's performance.
"It doesn't happen too often when guys get warned for not trying, so yes, of course, it does surprise me," he said.
"Davydenko is one of the best players in tight, close matches."
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