( CNN ) -- Two world records tumbled in the Aquatics Centre Sunday while France claimed two golds including a stunning upset in the men 's 4x100m freestyle relay . Dana Vollmer gave the United States a winning start on the second night of swimming finals with a commanding swim in the women 's 100m butterfly , becoming the first woman under the 56 seconds barrier with 55.98 seconds . The second world record of the night saw South African Cameron van der Burgh claim the men 's 100m breaststroke gold with a 58.46 seconds clocking . The French gold rush then started with Camille Muffat in the women 's 400m from American Allison Schmitt with defending champion Rebecca Adlington taking a battling bronze for Team GB . But it was the freestyle relay which provided the most thrilling finish and a real upset as France 's anchor leg swimmer Yannick Agnel overhauled Ryan Lochte to give his country its first gold in the event after a series of near misses . The United States looked to have the gold in the bag after an improved Michael Phelps had given them a commanding lead after the second leg . But Agnel powered past 400m individual medal winner Lochte for France to win in three minutes 9.93 seconds . Russia took the bronze ahead of fancied Australia . The silver medal for Phelps , so disappointing in his opening final Saturday , was his 17th in the Olympics , one behind the all-time record of Larisa Latynina , a Soviet gymnast . Earlier , Vollmer 's dominance had been total as she finished nearly a second clear of China 's Lu Ying with Alicia Coutts of Australia in third . She bettered the previous world record of 56.06 seconds set by Sweden 's Sarah Sjostrom , who finished fourth , at the 2009 world championships . `` I just relied on my strengths , '' Vollmer told gathered reporters . `` Just set it up well , passed a few people and charged it home . '' Van der Burgh also broke a mark set at the 2009 championships in Rome , shaving Australian Brenton Rickard 's old mark of 58.58 seconds . He dedicated his gold to his former training partner Alexander Dale Oen of Norway , who died at an Arizona training camp in April of heart failure as the result of a blood clot . `` I just have to pay tribute to Alexander Dale Oen tonight , I know he has been with me this year , I think he helped me finish the race in such a strong manner , '' van der Burgh said . `` Once you have become an Olympic champion that can never be taken away from you , '' he added after finishing ahead of Australian Christian Sprenger and American Brendan Hansen .
Dana Vollmer of USA breaks women 's 400m record . New world mark for Cameron van der Burgh in men 's 100 m breaststroke . Dana Vollmer of France takes womens ' 4x100m with Cameron van der Burgh third . France then stun France in men 's 4x100m freestyle relay .