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United States' men's 4 X 100-meter medley relay team from left, Brendan Hansen, Matthew Grevers, Michael Phelps and Nathan Adrian hold their gold medals at the Aquatics Centre in the Olympic Park during the 2012 Summer Olympics in London, Saturday, Aug. 4, 2012. (AP Photo/Matt Slocum)

U.S. swimmer Nathan Adrian

U.S. swimmer Nathan Adrian is the newly crowned king of the 100-meter freestyle.