LONDON _ The U.S. showed the depth of its Olympic swim roster Wednesday in the Aquatics Centre, winning two gold medals and setting an individual world record without anyone named Michael Phelps or Ryan Lochte involved.

In the night's most thrilling race, laidback Californian Nathan Adrian won the 100 meter freestyle by a fingernail over Australian favorite James Magnussen 47.52 seconds for Adrian, 47.53 for Magnussen.

American Rebecca Soni also set a world record in her best event, the 200 breaststroke _ although it was only in the semifinal and Soni will need another great performance to win gold Thursday. And the U.S. women's 4x200 freestyle relay team won a gold medal when Allison Schmitt started in second place on the anchor leg but then blew past the Australians to win her second gold medal in two days.

Phelps and Lochte watched Adrian's race from the ready room, where they were awaiting the semifinal heats of their 200 individual medley. They will face off in the final Thursday.

"We were cheering, cheering, cheering," Phelps said of Adrian's showdown with Magnussen. "And when he won, both Ryan and I went nuts."

Adrian out-touched Magnussen at the wall by 1/100th of a second. Known for being strongest in his first 50 meters, Adrian was only third at the halfway mark. "That's kind of comforting," Adrian said. "I like being the chaser. I don't necessarily like being chased."

It turned out Adrian had purposely saved a little more energy than usual for the second half of the race, however, and it saved him at the end.

Magnussen was chastened by the defeat. Before these Olympics, he had had enough confidence to call himself and his Australian freestyle relay teammates "weapons of mass destruction."

"I felt pretty much bulletproof coming into these Olympics," the Australian said. "It's very humbling. It's a pretty tough time to learn you're human ... . To have missed out twice in a row (Magnussen and the Australians were also favored in the 4x100 freestyle relay but finished fourth Sunday) is pretty shattering."

Soni's world-record mark was unexpected, coming as it did in a semifinal. She said she and her coach had decided to go ahead and go all out in the final 50 meters.

"I'm excited," said Soni, whose time of 2:20.00 edged the three-year-old world record set by Canada's Annamay Pierse by 0.12 seconds. "I have one more race. I felt good tonight so all I have to do is feel about the same tomorrow."

In the women's 4x200 freestyle, Schmitt trailed by 0.64 seconds when she dove into the pool, following swimmers Missy Franklin, Dana Vollmer and Shannon Vreeland. Schmitt had caught up to Australian Alicia Coutts before 100 meters were gone and ended up winning by 1.49 seconds.

"It was neck-and-neck the whole race," said Schmitt, who had won the women's 200 freestyle said. "I just wanted to bring up the energy and bring home the gold tonight in the relay."

Said Franklin: "Allison is a fighter. She can push through absolutely anything.