Key dates: July 28, 400 IM; July 29, 4x100 relay; Aug. 3, 100 butterfly Venue: Olympic Park Aquatics Centre Big story: Can the U.S. hold off the rest of the world? In total medals, almost certainly yes. In the prestige relay -- the 4x100, the one in which Jason Lezak saved Michael Phelps' chance at eight gold medals in Beijing -- maybe not. Australia or France -- possibly both -- could finish ahead of the U.S. Phelps intends to retire after the Olympics, so his final individual swim should be the 100 butterfly. He needs three medals to become the most decorated athlete in Olympic history. Ryan Lochte, like Phelps, will be swimming for seven medals. Lochte and Phelps are set to go head-to-head twice, in the 200 IM and 400 IM. Top U.S. prospects: With six wins, Phelps will finish his career with 20 gold medals -- double the next-closest Olympian. But Lochte is a heaven-sent rival for Phelps. There is also Cullen Jones, an African-American who leads learn-to-swim programs in the inner city, who is a medal favorite in the 50 free. And Matt Grevers is favored in the 100 backstroke after winning silver in Beijing. Others to watch: Brazil's Cesar Cielo won the 50 free in Beijing and has the fastest time in the world this year, with Jones and Anthony Ervin chasing him. Australia's James Magnussen, 21, is the phenom to watch -- to win the 100 free, and possibly to medal in the 50. Japan's Kosuke Kitajima could become the first male swimmer to win gold in the same event three consecutive times -- in the 100 or 200 breaststroke, or both -- unless Phelps beats him to it by winning the 400 IM on the first day. Little-known fact: Davis Tarwater, 28, announced his retirement from swimming on the next-to-last day of the U.S. Olympic Trials only to unretire in less than 24 hours when Phelps dropped out of the 200 creating a spot for him.
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