LONDON (Reuters) - Michael Phelps failed by a finger tip to become the first male swimmer to win the same event at three successive Olympics when he was piped to gold in the 200 meters butterfly, but the silver he won saw him equal the all-time record of 18 medals.

The American swimmer led going into the last few meters of his favorite race, but was tiring rapidly and had to settle for second when South Africa's Chad Le Clos ploughed through to snatch it on the final touch.

With the 4 x 200 meter freestyle relay still to come, Phelps looked set for another medal that would give him the undisputed status of greatest Olympian of all time.

Watching at poolside was Larisa Latynina, the Soviet gymnast who has held the record for decades with her haul - including nine golds - from the Games at Melbourne (1956), Rome (1960) and Tokyo (1964).

Latynina told Reuters earlier this month she had no doubt Phelps would overtake her in London and "I can only wish him well".

Phelps now has 14 gold medals, two silvers and two bronze.

In other action on day 4 of the Games, Germany won its first two golds, in equestrian eventing, and France its fourth, in canoe slalom - but host nation Britain was still seeking its first.

China, hoping to sweep all eight diving golds, made it three out of three so far and leads the overall medal table ahead of the United States and France.

China has vehemently rejected suggestions by an American coach that doping might be behind the astonishing performance of 16-year-old swimmer Ye Shiwen, who won Saturday's 400 meter individual medley by slashing more than a second from the world record.

American John Leonard, executive director of the World Swimming Coaches Association but not on the U.S. coaching staff in London, told Britain's Guardian newspaper: "Every time we see something ... 'unbelievable', history shows us that it turns out later on there was doping involved."

But officials and swimming greats lined up to urge that Ye's achievement be recognized, in the absence of any proof of guilt.

International Olympic Committee spokesman Mark Adams hinted strongly to reporters that Ye had passed her drug test at the Games.

"We would only comment if we had any adverse finding. I am not commenting, so you can draw your own conclusions," he said.

"I think we need to get real here. These are the world's best athletes competing at the highest level. We have a very, very strong drugs testing program. If there are cheats, we will catch them."

The Chinese team slapped back at Ye's accuser.

"Ye Shiwen has been seen as a genius since she was young, and her performance vindicates that," Xu Qi, head of the Chinese swimming team, told the news agency Xinhua.

"Don't use your own suspicions to knock down others. This shows lack of respect for athletes and for Chinese swimming."

Ye was chasing gold again on Tuesday in the 200 meters medley, where she is world champion.

INJUSTICE?

China briefly dominated women's swimming in the 1990s but their reign ended as fast as it began after a series of doping scandals.

"If it was another country there'd be fewer questions asked," said French coach Denis Auguin. "There's a bit of an injustice in that, even if the past shows us that there were some abnormal practices in China."

Ye covered the last 50 meters of freestyle faster than American Ryan Lochte, who won the equivalent men's event in the second-best time in history.

She issued a firm denial on Monday, telling the China News Service: "My results come from hard work and training and I would never use any banned drugs."

Far from being shut away from prying eyes in China, Ye is among a handful of Chinese who train in Australia, and has been tested regularly by the World Anti-Doping Agency (WADA).

"She's been through WADA's program and she's clean," said Colin Moynihan, chairman of the British Olympic Association.

"Ye Shiwen deserves recognition for her talent."

Some noted that Phelps had broken his first world record at 15. "Michael Phelps is a phenomenal swimmer," said British multiple short-course world champion Mark Foster. "Is she the Chinese Michael Phelps? Why not?"