London: Swimmer Michael Phelps won his 17th Olympic medal to take him closer to the all-time mark, but his US freestyle relay team were upstaged by France as records fell in the pool on Sunday's second day of competition at the London Games.
South Africa's Cameron Van der Burgh and American Dana Vollmer set world records in the men's 100 metres breaststroke and women's 100 butterfly, Van der Burgh denying Japan's Kosuke Kitajima in his bid to be the first male swimmer to win gold in the same event at three successive Olympics.
Overall, China took a commanding early lead in the rankings with 12 medals, six of them gold, ahead of the United States on 11 medals, including three golds.
Phelps won his first ever silver after swimming a storming second leg in the 4x100 freestyle relay to lift his overall medal tally to 17, just one shy of the all-time record held by Soviet gymnast Larisa Latynina.
But a flying anchor leg from France's Yannick Agnel snatched the gold from the fingertips of Phelps's team mate and great individual rival Ryan Lochte.
Australia, the fastest qualifiers and looking to notch a famous victory against their traditional rivals for pool supremacy, were soundly beaten into fourth.
Four years ago in Beijing Phelps won gold in each of the eight events that he swam. In London, after losing his 400 individual medley title to Lochte on Saturday, he has already tasted defeat twice in two days.
US swimmer Dana Vollmer ended a lifetime of frustration and battles with her health to win the 100 metres butterfly gold medal in world record time.
Swimming like a woman possessed, Vollmer sliced 0.08 seconds off a record set at the 2009 world championships in Rome before polyurethane bodysuits were banned.
Vollmer won a relay gold at Athens in 2004 a year after heart surgery. But she failed to qualify for Beijing in 2008 and did not return to form until she was diagnosed with an egg allergy and put on a special diet.
Cameron Van der Burgh also broke the world record, for the 100 breaststroke, to become the first South African man to win individual Olympic swimming gold.
His time trimmed 0.12 seconds off the record set by Australia's Brenton Rickard, also in Rome in 2009.
Japan's Kitajima, who won the breaststroke double at Athens in 2004 and Beijing four years later, was fifth, and will have to look to the 200 in London to try to make it three in a row.
There was a further pool gold for France when top-ranked Camille Muffat won the women's 400 freestyle ahead of Allison Schmitt of the United States and Britain's defending champion, Rebecca Adlington.