ZURICH, Switzerland Martina Hingis said Thursday she has been accused of testing positive for cocaine at Wimbledon, and then announced her retirement from professional tennis.
Hingis, a five-time Grand Slam champion and former Wimbledon winner, denied using cocaine.
"I find this accusation so horrendous, so monstrous that I've decided to confront it head on by talking to the press," she said. "I am frustrated and angry. I believe that I am absolutely 100 percent innocent."
The 27-year-old Swiss player lost in the third round at Wimbledon to Laura Granville, 6-4, 6-2.
Hingis returned to the sport two years ago after a four-year absence because of injuries.
She won three straight Australian Open titles from 1997-99, and Wimbledon and the U.S. Open championships in 1997.
Hingis, who lost in the third round of the U.S. Open, hasn't played since her second-round loss to Peng Shuai of China, 7-5, 6-1, in Beijing on Sept. 19.
Hingis said she was accused by "an outsource testing company" of taking cocaine during Wimbledon. She said she was "shocked and appalled" when notified that her urine sample came back positive after the loss to Granville.
"They say that cocaine increases self-confidence and creates a type of euphoria," she said in a statement. "I don't know. I only know that if I were to try to hit the ball while in any state of euphoria, it simply wouldn't work.
"I would think that it would be impossible for anyone to maintain the coordination required to play top class tennis while under the influence of drugs. And I know one other thing I would personally be terrified of taking drugs."
Hingis said she later underwent a privately arranged hair test which came back negative for cocaine. The official backup "B" sample test on her Wimbledon urine sample, however, tested positive for the drug.
Hingis said she hired an attorney who found "various inconsistencies" with the urine sample taken during Wimbledon.
"He is also convinced that the doping officials mishandled the process and would not be able to prove that the urine that was tested for cocaine actually came from me," she said.
Hingis said it could take years to fight her case and decided it was time to retire.
"I have no desire to spend the next several years of my life reduced to fighting against the doping officials," she said. "The fact is that it is more and more difficult for me, physically, to keep playing at the top of the game.
"And frankly, accusations such as these don't exactly provide me with motivation to even make another attempt to do so."
WTA Tour chief executive Larry Scott said the tour had not received any official information about a positive test and "as a result we are not in a position to comment on the matter."
"However, it is important to remember that in the area of anti-doping, all players are presumed innocent until proven otherwise," Scott said.
Referring to her retirement, he said, "Martina Hingis is a tremendous champion and a fan favorite the world over. In her most recent comeback, she proved again that she can perform at the very highest levels of the game."