Eric Shanteau (L), Aaron Peirsol (C) and Michael Phelps of the U.S. react during the men's 4x100 medley relay swimming final at the World Championships in Rome August 2, 2009.

Michael Phelps (R) of the U.S. reacts during the men's 4x100 medley relay swimming final at the World Championships in Rome August 2, 2009.

Michael Phelps (R) of the U.S. celebrates with his mother Deborah (C) and his sister Whitney his gold medal win in the men's 100m butterfly swimming final at the World Championships in Rome August 1, 2009.

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ROME - AUGUST 02: Swimmers compete in the Men's 4x 100m Medley Relay Final during the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Michael Phelps of the United States and Federica Pellegrini of Italy receive an award after the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Michael Phelps of the United States receives an award after the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

Gold medallist Michael Phelps (R) of the U.S. is congratulated by silver medallist Milorad Cavic of Serbia on the podium after the men's 100m butterfly swimming final at the World Championships in Rome August 1, 2009.

Michael Phelps (R) of the U.S. and Milorad Cavic of Serbia pose with their medals after the men's 100m butterfly swimming final at the World Championships in Rome August 1, 2009.

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ROME - AUGUST 02: Hillary Phelps and Debbie Phelps, sister and mother of Michael Phelps of the United States celebrate as they watch his victory in the Men's 4x 100m Medley Relay Final during the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

Michael Phelps (R) of the U.S. and Milorad Cavic of Serbia pose with their medals after the men's 100m butterfly swimming final at the World Championships in Rome August 1, 2009.

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ROME - AUGUST 02: Aaron Peirsol, Eric Shanteau, Michael Phelps and David Walters of the United States receive the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final at the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Aaron Peirsol, Eric Shanteau, Michael Phelps and David Walters of the United States receive the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final at the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Michael Phelps of the United States receives the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final during the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Michael Phelps of the United States receives the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final during the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Michael Phelps of the United States receives the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final during the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Michael Phelps of the United States receives the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final during the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Aaron Peirsol, Eric Shanteau, Michael Phelps and David Walters of the United States receive the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final at the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

Gold medallist Michael Phelps (L) of the U.S. and silver medallist Milorad Cavic of Serbia celebrate on the podium after the men's 100m butterfly swimming final at the World Championships in Rome August 1, 2009.

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ROME - AUGUST 02: Aaron Peirsol, Eric Shanteau, Michael Phelps and David Walters of the United States receive the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final at the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Aaron Peirsol, Eric Shanteau, Michael Phelps and David Walters of the United States receive the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final at the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Aaron Peirsol, Eric Shanteau, Michael Phelps and David Walters of the United States receive the gold medal during the medal ceremony for the Men's 4x 100m Medley Relay Final at the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

Michael Phelps (R) of the U.S. and Milorad Cavic of Serbia compete in the men's 100m butterfly swimming final at the World Championships in Rome August 1, 2009. Picture taken with fisheye lens.

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ROME - AUGUST 02: Aaron Peirsol, Eric Shanteau and Michael Phelps of the United States celebrate victory in the Men's 4x 100m Medley Relay Final during the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Michael Phelps of the United States competes in the Men's 4x 100m Medley Relay Final during the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.

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ROME - AUGUST 02: Michael Phelps of the United States competes in the Men's 4x 100m Medley Relay Final during the 13th FINA World Championships at the Stadio del Nuoto on August 2, 2009 in Rome, Italy.