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Michael Phelps competes in the championship final of the Men's 100 m Butterfly during Day Six of the 2012 U.S. Olympic Swimming Team Trials at CenturyLink Center on July 1, 2012 in Omaha, Nebraska. (Photo by Jamie Squire/Getty Images)

U.S. Olympic swim trials

Athletes compete for a place on the U.S. London Olympic swimming team.