Ye Shiwen, China's 16-year-old swimming champion, really is that fast, Olympics officials say.
The gold medallist and world record holder has passed all the tests for performance-enhancing drugs, the chairman of the British Olympic Association said today.
"She been through [the World Anti-Doping Agency's] program and she's clean," Lord Colin Moynihan told a press conference. "That's the end of the story. Ye Shiwen deserves recognition for her talent."
Moynihan condemned the speculation that her success might be due to something else.
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A senior US coach stoked the rumors yesterday when he called Ye's record-breaking performance in the 400m medley "disturbing" and "suspicious."
"History in our sport will tell you that every time we see something, and I will put quotation marks around this, 'unbelievable,' history shows us that it turns out later on there was doping involved," John Leonard, executive director of the World Swimming Coaches Association, told The Guardian.
Ye denied any allegation of doping and put her form down to "good and scientific training," Chinese news agency Xinhua reported.
Some suggested that other countries were unwilling to believe that China could produce a champion.
"I think it is not proper to single Chinese swimmers out once they produce good results. Some people are just biased," China's top anti-doping official, Jiang Zhixue, told Xinhua, according to The Guardian's translation.
"We never questioned Michael Phelps when he bagged eight gold medals in Beijing."
Much of the disbelief has centered on the fact that Ye was able to accelerate dramatically at the end of the race, swimming the final 50m quicker than her fastest male equivalent, Ryan Lochte of Team USA.
Chinese coach Xu Qi told Xinhua that the comparison was "meaningless," since Ye was behind and needed to do her best to take the lead, while Lochte was already out in front "and didn't need to do his utmost."
Lochte himself said he wasn't sure he could have overtaken Ye: "She's fast and if she was out there with me, she might be able to beat me too."