Matt Grevers of the U.S. (L) and his team mate Nick Thoman hold their gold and silver medals respectively during the men's 100m backstroke victory ceremony at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/Michael Dalder (BRITAIN - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers of the U.S. smiles with his gold medal during the men's 100m backstroke victory ceremony at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/Michael Dalder (BRITAIN - Tags: SPORT SWIMMING SPORT OLYMPICS TPX IMAGES OF THE DAY)

Matt Grevers of the U.S. celebrates with his gold medal during the men's 100m backstroke victory ceremony at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/Toby Melville (BRITAIN - Tags: SPORT OLYMPICS SPORT SWIMMING)

Matt Grevers of the U.S. starts his men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. Grevers set a Olympic record with a time of 52.16 seconds. REUTERS/Tim Wimborne (BRITAIN - Tags: SPORT SWIMMING OLYMPICS)

Matt Grevers of the U.S. celebrates his gold medal win with his team mate Nick Thoman (L) in the men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/Toby Melville (BRITAIN - Tags: SPORT OLYMPICS SPORT SWIMMING)

Matt Grevers of the U.S. (R) is congratulated by compatriot Nick Thoman after he won the men's 100m backstroke final during the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. Grevers set an Olympic record with a time of 52.16 seconds, while Thoman came in second. REUTERS/Toby Melville (BRITAIN - Tags: SPORT OLYMPICS SWIMMING)

Matt Grevers of the U.S. celebrates after winning the men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. Grevers set a Olympic record with a time of 52.16 seconds. REUTERS/Toby Melville (BRITAIN - Tags: SWIMMING SPORT OLYMPICS)

Matt Grevers of the U.S. celebrates after winning the men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. Grevers set a Olympic record with a time of 52.16 seconds. REUTERS/Tim Wimborne (BRITAIN - Tags: SPORT SWIMMING OLYMPICS)

Matt Grevers of the U.S. celebrates after winning the men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. Grevers set a Olympic record with a time of 52.16 seconds. REUTERS/Toby Melville (BRITAIN - Tags: SWIMMING SPORT OLYMPICS)

Matt Grevers of the U.S. reacts after he won the men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/Toby Melville (BRITAIN - Tags: SPORT OLYMPICS SPORT SWIMMING)

Matt Grevers of the U.S. reacts after he won the men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/Toby Melville (BRITAIN - Tags: SPORT OLYMPICS SPORT SWIMMING)

Matt Grevers of the U.S. reacts after he won the men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/Toby Melville (BRITAIN - Tags: SPORT OLYMPICS SPORT SWIMMING)

Matt Grevers of the U.S. (L) celebrates after winning the men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. Grevers set a Olympic record with a time of 52.16 seconds. REUTERS/Michael Dalder (BRITAIN - Tags: SPORT SWIMMING OLYMPICS)

Matt Grevers (L) of the U.S. celebrates with compatriot Nick Thomas after winning the men's 100m backstroke final at the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/Michael Dalder (BRITAIN - Tags: SPORT OLYMPICS SPORT SWIMMING)

Matt Grevers of the U.S. celebrates after winning the men's 100m backstroke final during the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/David Gray (BRITAIN - Tags: SPORT OLYMPICS SPORT SWIMMING TPX IMAGES OF THE DAY)

Matt Grevers of the U.S. (L) is congratulated by compatriot Nick Thoman after he won the men's 100m backstroke final during the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. Grevers set an Olympic record with a time of 52.16 seconds, while Thoman came in second. REUTERS/David Gray (BRITAIN - Tags: SPORT OLYMPICS SWIMMING TPX IMAGES OF THE DAY)

Matt Grevers of the U.S. starts in the men's 100m backstroke final during the London 2012 Olympic Games at the Aquatics Centre July 30, 2012. REUTERS/David Gray (BRITAIN - Tags: SPORT OLYMPICS SPORT SWIMMING)

Matt Grevers (L), winner of the men's 100m backstroke final is congratulated by Adolph Kiefer, winner of the 1936 Olympic gold medal for the 100m backstroke during the U.S. Olympic swimming trials in Omaha, Nebraska, June 27, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers celebrates before receiving his gold medal for the men's 100m backstroke final during the U.S. Olympic swimming trials in Omaha, Nebraska, June 27, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers celebrates before receiving his gold medal for the men's 100m backstroke final during the U.S. Olympic swimming trials in Omaha, Nebraska, June 27, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers (R) and Nick Thoman celebrate after finishing first and second in the men's 100m backstroke final during the U.S. Olympic swimming trials in Omaha, Nebraska, June 27, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers celebrates after winning the men's 100m backstroke final during the U.S. Olympic swimming trials in Omaha, Nebraska, June 27, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers celebrates with fans after winning the men's 100m backstroke final during the U.S. Olympic swimming trials in Omaha, Nebraska, June 27, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers celebrates after winning the men's 100m backstroke final during the U.S. Olympic swimming trials in Omaha, Nebraska, June 27, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers celebrates after winning the men's 100m backstroke final during the U.S. Olympic swimming trials in Omaha, Nebraska, June 27, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers celebrates after winning the men's 100m backstroke final during the U.S. Olympic swimming trials in Omaha, Nebraska, June 27, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING SPORT OLYMPICS)

Matt Grevers swims his men's 100m backstroke heat during the U.S. Olympic swimming trials in Omaha, Nebraska, June 26, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING)

Matt Grevers swims his men's 100m backstroke heat during the U.S. Olympic swimming trials in Omaha, Nebraska, June 26, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING)

Matt Grevers swims his men's 100m backstroke heat during the U.S. Olympic swimming trials in Omaha, Nebraska, June 26, 2012. REUTERS/Jeff Haynes (UNITED STATES - Tags: SPORT SWIMMING)

Nick Brunelli of the U.S. (L), along with teammates Garrett Weber-Gale (2nd L), and Matt Grevers celebrate with Ricky Berens (in water) after winning the Men's 4x100 meter Freestyle during the Mutual of Omaha Duel in the Pool swimming competition at the Georgia Tech Aquatic Center in Atlanta, Georgia December 17, 2011. REUTERS/Tami Chappell (UNITED STATES - Tags: SPORT SWIMMING) 

Matt Grevers of the U.S. swims in the men's 100-meter backstroke during the Mutual of Omaha Duel in the Pool swimming competition at the Georgia Tech Aquatic Center in Atlanta December 17, 2011. REUTERS/Tami Chappell (UNITED STATES - Tags: SPORT SWIMMING) 

Matt Grevers of the U.S. gives a thumbs-up after winning the Men's 100 meter Backstroke during the Mutual of Omaha Duel in the Pool swimming competition at the Georgia Tech Aquatic Center in Atlanta, Georgia December 17, 2011. REUTERS/Tami Chappell (UNITED STATES - Tags: SPORT SWIMMING) 

Gold medallist Aaron Peirsol (2nd L) of the U.S. stands with silver medallist and compatriot Matt Grevers (L) and bronze medallists Hayden Stoeckel (2nd R) of Australia and Arkady Vyatchanin (R) of Russia after the men's 100 meters backstroke swimming final at the National Aquatics Center during the Beijing 2008 Olympic Games August 12, 2008. REUTERS/David Gray (CHINA) 

Gold medallist Aaron Peirsol (2nd L) of the U.S. stands with silver medallist and compatriot Matt Grevers (L) and bronze medallists Hayden Stoeckel (2nd R) of Australia and Arkady Vyatchanin (R) of Russia after the men's 100 meters backstroke swimming final at the National Aquatics Center during the Beijing 2008 Olympic Games August 12, 2008. REUTERS/Wolfgang Rattay (CHINA) 

Gold medallist Aaron Peirsol (2nd R) of the U.S. stands with silver medallist and compatriot Matt Grevers (R) and bronze medallists Hayden Stoeckel (L) of Australia and Arkady Vyatchanin (2nd L) of Russia after the men's 100 meters backstroke swimming final at the National Aquatics Center during the Beijing 2008 Olympic Games August 12, 2008. REUTERS/Wolfgang Rattay (CHINA) 

Aaron Peirsol of the U.S. celebrates winning the gold medal and his compatriot Matt Grevers (R) the silver medal during the men's 100m backstroke swimming final at the National Aquatics Center during the 2008 Beijing Olympics, August 12, 2008. REUTERS/Jason Reed (CHINA) 

Aaron Peirsol (R) of the U.S. stands with his gold medal as teammate Matt Grevers stands with his silver medal for the men's 100m backstroke swimming final at the National Aquatics Centre during the Beijing 2008 Olympic Games, August 12, 2008. REUTERS/Jerry Lampen (CHINA) 

Aaron Peirsol (R) of the U.S. stands with his gold medal as teammate Matt Grevers stands with his silver medal for the men's 100m backstroke swimming final at the National Aquatics Centre during the Beijing 2008 Olympic Games, August 12, 2008. REUTERS/Jerry Lampen (CHINA) 

Gold medallist Aaron Peirsol (2nd L) of the U.S. stands with silver medallist and compatriot Matt Grevers (L) and bronze medallists Hayden Stoeckel (2nd R) of Australia and Arkady Vyatchanin (R) of Russia after the men's 100 meters backstroke swimming final at the National Aquatics Center during the Beijing 2008 Olympic Games August 12, 2008. REUTERS/David Gray (CHINA) 

Gold medallist Aaron Peirsol (2nd R) of the U.S. stands with silver medallist and compatriot Matt Grevers (R) and bronze medallists Hayden Stoeckel (L) of Australia and Arkady Vyatchanin (2nd L) of Russia after the men's 100 meters backstroke swimming final at the National Aquatics Center during the Beijing 2008 Olympic Games August 12, 2008. REUTERS/Wolfgang Rattay (CHINA) 

Gold medallist Aaron Peirsol (2nd L) of the U.S. stands with silver medallist and compatriot Matt Grevers (L) and bronze medallists Hayden Stoeckel (2nd R) of Australia and Arkady Vyatchanin (R) of Russia after the men's 100 meters backstroke swimming final at the National Aquatics Center during the Beijing 2008 Olympic Games August 12, 2008. REUTERS/Wolfgang Rattay (CHINA) 

Aaron Peirsol of the U.S. celebrates winning the gold medal with his compatriot Matt Grevers (R), who won the silver medal, in the men's 100m backstroke swimming final at the National Aquatics Center during the 2008 Beijing Olympics, August 12, 2008, REUTERS/Jerry Lampen (CHINA) 

Aaron Peirsol of the U.S. celebrates winning the gold medal and his compatriot Matt Grevers (R), the silver medal, in the men's 100m backstroke swimming final at the National Aquatics Center during the 2008 Beijing Olympics, August 12, 2008, REUTERS/Jerry Lampen (CHINA) 

Matt Grevers of the U.S. comes off the wall at the start of his men's 100 meters backstroke swimming semifinal at the National Aquatics Center during the Beijing 2008 Olympic Games August 11, 2008. REUTERS/Adrees Latif (CHINA) 

Ben Wildman-Tobriner (top L), Nathan Adrian (top C), Cullen Jones and Matt Grevers (bottom) of the U.S. celebrate after winning their men's 4x100m freestyle relay swimming heat at the National Aquatics Center during the Beijing 2008 Olympic Games August 10, 2008. REUTERS/David Gray (CHINA) 

Ben Wildman-Tobriner (top L), Nathan Adrian (top C), Cullen Jones and Matt Grevers (bottom) of the U.S. celebrate after winning their men's 4x100m freestyle relay swimming heat at the National Aquatics Center during the Beijing 2008 Olympic Games August 10, 2008. REUTERS/David Gray (CHINA) 

Aaron Peirsol of the U.S. celebrates winning the gold medal and his compatriot Matt Grevers (R) the silver medal during the men's 100m backstroke swimming final at the National Aquatics Center during the 2008 Beijing Olympics, August 12, 2008. REUTERS/Jason Reed (CHINA)