Whenever an athlete turns in a remarkable performance eyebrows are raised and the whispers begin about drug use.
Chinese swimmer Ye Shiwen has found herself in the middle of a controversy at the London Olympics after her gold medal win in the 400-metre individual medley. But Mark Foster, a former British Olympic swimmer, has come to Ye's defence.
"There's no evidence at all and I've always believed in a simple principle, innocent until proven guilty,'' Foster wrote in a British newspaper.
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"Perhaps the Chinese are just doing things differently, maybe diet, maybe training. If they have developed something new, you would have thought it would aid the whole team, not just two swimmers.''
The 16-year-old Ye set a world record of four minutes, 28.43 seconds Saturday night. The closest finisher touched the wall almost three seconds behind. Ye swam the final 25 metres of her race faster than American Ryan Lochte swam the final 25 metres in winning gold in the men's 400 IM.
That raised suspicions in people like U.S. coach John Leonard, the executive director of the World Swimming Coaches Association. He called Ye's performance "'unbelievable.''
"No coach that I spoke to yesterday could ever recall seeing anything remotely like that in a world level competition," Leonard told the Guardian newspaper.
Not only was Ye's time faster than Lochte's final leg, her overall time was five seconds quicker than her previous best.
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"'All those things, I think, legitimately call that swim into question," Leonard said.
Ye has denied using performance-enhancing substances.
"There's absolutely no problem with the doping," Ye said Monday, according to a translation provided by the official Olympic News Service. "The Chinese team has always had a firm policy about doping."
On Monday Ye posted the fastest qualifying time in the 200 IM. Her time of 2:08.90 is the best time in the world this year. She was 1.5 seconds faster than the runner-up.
Foster said Ye might be a female Michael Phelps.
"Someone taking the sport to a new level who will become a legend,'' he said. "China could not have a wider talent pool to draw from. Their huge population is a resource other countries don't have.
"And when Phelps won eight golds in Beijing, the Chinese and the rest of the world didn't start asking what the US were doing. We all just agreed he was amazing. ...I want to believe what I see, unless I discover otherwise.''
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Ye has never tested positive for any banned substances.
"It was a five-second best time and it was the way she did it, as well,'' said Foster. "Bearing in mind she is 16 years of age, and when you are young you do some big best times... it can be done."
Talk of drug cheating is not new to the Chinese swimming community.
Last month news broke that 16-year-old Li Zhesi tested positive for the performance-enhancing drug EPO. Li was a member of the Chinese team that won gold in the women's 4x100-metre medley relay at the 2009 world championships in Rome, and silver at the 2011 worlds in Shanghai.
Ye finished fifth in the 400 IM at the 2011 world championships. She is the reigning world champion in the women's 200 IM.