LONDON — Dana Vollmer won a gold medal at the Olympics and set a world record, too. Not bad for someone who didn't even qualify four years ago. On a night featuring a relay duel between the Australians and the Americans, Vollmer got things started with a bang Sunday in the 100-meter butterfly. She was third at the turn but powered to the wall for a time of 55.98 seconds, beating the record of 56.06 set by Sweden's Sarah Sjostrom in a since-banned high-tech bodysuit at the 2009 world championships. The American dropped back her head when saw the time, then broke into a huge smile, slapped the water and pumped her fists. “I'm on top of the world right now.” she said. “I still know I can go faster.” Lu Ying gave China another medal at the Olympic Aquatics Centre, taking silver in 56.87. Australia's Alicia Coutts grabbed the bronze in 56.94. It was a tough night for Sjostrom. Not only did she lose her world record, she didn't even get a medal, touching fourth in 57.17. Vollmer was the second swimmer to set a world record at the London Games, and only the fourth to break a mark set during the rubberized suit era. Those suits were banned after an astonishing 43 world records were set at the 2009 world championships. The big race on the second night of swimming was the men's 400m freestyle relay, which figured to be a duel between defending world champion Australia and the US, which won the Olympic title four years ago. The Americans sent out their big guns, going with Michael Phelps and Ryan Lochte in hopes of knocking off a favored Aussies team that included James “The Missile” Magnussen and James “The Rocket” Roberts. Nathan Adrian and Cullen Jones also were swimming for the US, which changed up its entire lineup after qualifying second in the morning preliminaries. The Aussies posted the fastest qualifying time with a quartet that included Magnussen and Roberts. They changed up the other two spots, going with Matt Targett and Eamon Sullivan. China wins diving gold China's Wu Minxia won her third synchronized three-meter springboard Olympic gold medal winning the final with He Zi Sunday. In the first of China's quest for all eight diving gold medals at London, Wu and He dominated the competition with 346.20 points to claim victory. The United States pair of Abigail Johnston and Kelci Bryant took silver with 321.90 with Canada's Emilie Heymans and Jennifer Abel claiming bronze with 316.80. The Chinese pair's highlights were a competition-high 80.10 points for a reverse 2.5 somersault and a back 2.5 somersault. Wu won the last two synchronized gold medals with Guo in Athens and Beijing. — Agencies