Ye, just 16, goes for a second gold of the Games in the 200m individual medley, just days after her lightning freestyle leg in the 400m individual medley propelled her to a new world record.
The schoolgirl timed 58.68sec in the last 100 metres, a whisker off US winner Ryan Lochte’s time for the equivalent section in the men’s event. Astonishingly, her final lap was quicker than the American.
It was a performance that has prompted suspicions over her performances but Ye and the Chinese authorities have slammed the critics, claiming the Chinese are being unfairly singled out.
Ye, who late Monday set the world’s fastest time in the 200m individual medley semi-finals, has denied foul play.
“The Chinese athletes, including the swimmers, have undergone nearly 100 drug tests since they arrived here,” Jiang Zhixue, the head of anti-doping at China’s General Administration of Sport, told Xinhua news agency.
“Many were also tested by the international federations and the British anti-doping agency. I can tell you that so far there was not a single positive case.”
He added: “I think it is not proper to single Chinese swimmers out once they produce good results. Some people are just biased.
“We never questioned Michael Phelps when he bagged eight gold medals in Beijing.”
Phelps himself can make Olympic history by winning two medals of any colour in the pool in the evening.
The American goes in the 200m butterfly final which he has won for the last two Olympics and then will join his US teammates as they defend their 4x200m freestyle relay.
Phelps, 27, is having a rollercoaster Games after slumping to a shock fourth in the 400m individual medley dominated by his fellow American Ryan Lochte and then had to settle for silver in the 4x100m freestyle relay.
That medal took Phelps’ Olympic career total to 17, leaving him just one short of the all-time biggest career haul of 18 won by Soviet gymnast Larisa Latynina.
Phelps owns the four fastest times in history in the 200m butterfly, and his world record of 1min 51.51sec is more than one second faster than the second-best performer in history, Hungarian Laszlo Cseh at 1:52.70.
“I made my first Olympic team in this event,” Phelps noted.
Australia’s James Magnussen has a lot to prove as he tries to shrug off a painful relay loss when he starts his bid for the 100m freestyle title.
Magnussen, 21, arrived in London as the overwhelming favorite in the blue riband sprint after bursting on to the international stage with a World Championships triumph in Shanghai last year.
But Magnussen failed to produce the goods in the 4×100 freestyle relay won by surprise packages France on Sunday and must now hope for a confidence-restoring performance against a field that includes world record-holder Cesar Cielo.
France’s Camille Muffat and US teen sensation Missy Franklin go head-to-head in the women’s 200m freestyle final as they both attempt to win a second gold of these Games, although Franklin must do so from lane eight.
In the gymnastics, China’s hopes of emulating the success of their men’s team by retaining the team title appear slim after they were outclassed by the United States in qualifying.
US superstars Kobe Bryant, LeBron James and their star-studded ensemble cast are expected to crush minnows Tunisia in their second match of the basketball tournament.
After easing past France in their opener, the Americans looked ominously determined to prove they are superior to the original Dream Team which lit up the 1992 Barcelona Olympics.
In three-day eventing, Queen Elizabeth II’s granddaughter Zara Phillips has a chance of picking up a medal with the British team who go into the final day lying behind defending champions Germany.
