Coutts gets the full set of medals, Magnussen’s return to form, Barratt’s best individual effort and tears for Rice. Jim Wilson and Nicole Livingstone analyse day 4 at the Aquatic Centre.

CHINESE swimming sensation Ye Shiwen Ye has delivered an 'absolutely not' answer to questions about whether she has used performance-enhancing drugs.

Sixteen-year-old schoolgirl Ye shattered Stephanie Rice's 400 individual medley record earlier this week, snapping more than a second off the old mark as she steamrolled her way to gold.

And she claimed a second win this morning when she took out the final of the 200m individual medley, edging out another Australian, Alicia Coutts on her way to an Olympic record time.

"In other countries, other swimmers have won multiple golds and nobody has said anything," Ye Shiwen told a news conference after her 200m IM win.

"How come people criticise me just because I have won multiple golds?"

Asked directly if she had ever used performance enhancing substances, the 16-year-old said: "Absolutely not."

She said her success and that of other young swimmers such as 17-year-old American Missy Franklin was because of 'our training' and because 'we work really hard'.

What has caused the world to raise its eyebrows was Ye swam the final lap of her freestyle leg in the 400IM (in 28.93sec) faster than men's champion Ryan Lochte (29.10sec), and faster than Michael Phelps.

But Coutts says she was just beaten by a better swimmer.

"I like to believe in innocent until proven guilty," Coutts said.

"As far as I'm concerned she's innocent and I think she's an amazing swimmer and it's just amazing to be as close as I was."

No man, bar the greatest swimmer and Olympian of all time Phelps, has ever swum a lap of the 400IM faster than Ye.

It is the first time in Olympic history a woman has swam faster in any lap than a male gold medallist.

Ye's father, Ye Qingsong, told Chinese news portal Tencent that he accepted it was "normal for people to be suspicious" but added: "The western media has always been arrogant, and suspicious of Chinese people."

As the world winces, China's two Australian coaches have defended their swimmers and their brilliant times.

Ye trains in blocks in Queensland with Australian coaches Ken Wood and Denis Cotterell, under contracts with the Chinese.

Wood defended the Chinese swimmers by saying they simply work hard.

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The Australian coach became famous four years ago when it emerged he was working with the Chinese swimmers ahead of the Beijing Olympics, which included sharing the training secrets of his Australian swimmer Jessica Schipper, only for a Chinese swimmer he trained to beat his own Australan swimmer in the final.

Wood is paid bonuses for Olympic gold medals and personal bests, and received a bonus for Ye's 200m medley gold medal at last year's world championships in Shanghai.

It is rumoured the Australian coaches are on a deal paying them bonuses of $250,000 a gold medal, $150,000 for silver and $100,000 for bronze.

"I get paid per month, per swimmer, four times more than I do with my home swimmers," Wood told Associated Press.

"China is putting a lot of money into its program and I am only too happy to work with them.

"The whole Chinese philosophy is that they want to be the best they can."

China has had a troubled history with doping, particularly in the 1990s when drug-fuelled muscle bound swimmers dominated the sport until eventually banned for drugs. Several Chinese swimmers were kicked out of Australia on the eve of the World Championships in Perth in 1997, with one held at customs with numerous vials of drugs.

Drawing extra suspicion to the Chinese assault in London is their training habits.

Ye and the other Chinese swimmers, which include 400m men's champion Yang Sun, who won China's first gold medal on Saturday, fly to Australia for training blocks with their Australian coaches, then return to China to train in virtual solitude.

Wood is contracted to the Chinese Swimming Association and is involved with 15 of their swimmers in London, plus five relay swimmers, who train at his academy north of Brisbane.

Their training habits - short blocks in Australia before returning to China - raise suspicions that the Chinese swimmers are coming to Australia for technical improvement before returning to China where their technical advancements are then assisted.

The International Olympic Committee's medical commission chairman, Arne Ljungqvist, revealed that, along with the 5000 drug tests that will be conducted at these Games, an investigation unit has been formed for the first time to specifically target athletes based on information.

However he said there was no evidence China was doping.

Referring specifically to Ye's performances, he said: "It is very sad that an unexpected performance be surrounded by suspicions."

Ljundgqvist confirmed what the rest of the world is thinking after the dramatic performances from the Chinese swimmers.

"Suspicion is halfway an accusation that something is wrong," he said.

"I don't like that. I would rather have facts."

The Chinese have reacted angrily to accusations of doping, with Chinese swim chief Xu Qi asking why couldn't China simply have a talented swimmer?

After her race Ye said: "There is no problem with doping, the Chinese team has a firm policy so there is no problem with that".

Easlier, a top US coach hinted at possible doping in the case of Ye, the 16-year-old who put in a lighting-quick freestyle leg in a world record 400m IM race.

But an outraged China camp aide there's no reason Ye can't simply be the next Ian Thorpe or Michael Phelps.

"Michael Phelps won eight gold medals at the Beijing Games, and American swimmer Missy Franklin is also incredible," the swim chief, Xu Qi, told Xinhua news agency this morning.

"Why can't China have a talented swimmer?"

John Leonard, executive director of the World Swimming Coaches Association, told The Guardian that the 16-year-old's freestyle leg in her IM swim was simply "impossible".

"The one thing I will say is that 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," Leonard told the British newspaper.

"That last 100m was reminiscent of some old East German swimmers, for people who have been around a while.

"It was reminiscent of the 400m individual medley by a young Irish woman in Atlanta."

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Leonard was referring to Michelle de Bruin, who emerged as a triple gold-medallist at the 1996 Games (where she competed under maiden name Smith) but was banned for four years in 1998 for tampering with a urine sample.

"Any time someone has looked like superwoman in the history of our sport they have later been found guilty of doping," he said, adding: "I have been around swimming for four-and-a-half decades now.

"If you have been around swimming you know when something has been done that just isn't right. I have heard commentators saying 'well she is 16, and at that age amazing things happen'. Well yes, but not that amazing. I am sorry."

With the swim, Ye took nearly seven seconds off her time at last year's world championships.