Exciting moments and major surprises have already marked the London 2012 Olympic Games, which were only in their first full day on Saturday.

The biggest upset came in the afternoon, when American swimmers Michael Phelps and Ryan Lochte squared off in the men's 400-meter individual medley. Lochte won the gold, while Phelps failed to reach a spot on the podium, as he finished fourth.

Phelps' coach Bob Bowman was "not pleasantly" surprised at the fourth-place finish, according to the New York Daily News. And Phelps himself acknowledged it was "just a crappy race."

Phelps still holds the world record for the 400-meter individual medley, which he set with a time of 4:03.84 at the 2008 Beijing Olympics.

The swimming competitions Saturday also saw the first new world record set at this installment of the Olympics: China's Ye Shiwen established the record for the women's 400-meter individual medley with a time of 4:28.43, as she bested the American Elizabeth Beisel and the Chinese Li Xuanxu.

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In beach volleyball, both the American men's and women's teams reigned supreme. The American women's team of Misty May-Treanor and Kerri Walsh-Jennings topped the Australian team in two straight sets. The American men's team of Jake Gibb and Sean Rosenthal did likewise versus the South African team.

In basketball, the U.S. women's squad extended its Olympics winning streak to 34 games, with the Croatia team its victim this time around. While the Croatians fought hard in the beginning, the Americans put it all together at the end for a 81-56 win.

Finally, the U.S. men's gymnastics team is leading in the qualification-round standings with 275.342 points.

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