The men's 100-meter butterfly was first held at the Olympic Games in 1968, when American Douglas Russell won in a time of 55.9. Since then, the event has been contested in each Olympic Games.
Here's a little bit about the last five men to win the event at the Olympic Games:
Michael Phelps: In 2008, the 100-meter butterfly represented just one of eight gold medals won by Michael Phelps. That year, the American swam the event in a time of 50.58 and out-touched Serbia's Milorad Cavic by 0.01 of a second. Phelps also won the 100-meter butterfly at the 2004 Olympic Games, where he finished just 0.04 of a second ahead of American teammate Ian Crocker.
Lars Frolander: Swedish swimmer Lars Frolander won the 100-meter butterfly at the 2000 Olympic Games in Sydney in a time of 52.00. Frolander also earned silver medals at the 1992 and 1996 Olympic Games in the 4x200-meter freestyle relay. To date, Frolander has competed in five Olympic Games.
Denis Pankratov: Denis Pankratov completed the butterfly double when he earned the gold medal in the 100- and 200-meter butterfly events at the 1996 Olympic Games. That year the Russian, who was known for swimming much of his races underwater, also earned a silver medal in the 4x100-meter medley relay.
Pablo Morales: American Pablo Morales won the 100-meter butterfly at the 1992 Olympic Games. He also earned the silver medal in the 100- and 200-meter butterfly events at the 1984 Olympic Games before failing to qualify for the 1988 Olympic Games. After his disappointing performance at the 1988 Olympic trials, Morales briefly retired before returning to the sport in order to win the gold medal in 1992.
Anthony Nesty: When he won gold in the 100-meter butterfly, Anthony Nesty became the first Olympic medalist ever for Suriname and just the second black swimmer to earn an Olympic medal. Four years later, at the 1992 Olympic Games in Barcelona, Nesty went on to win the bronze medal in the 100-meter butterfly.
More from this author: The Last Five Women to Win the 100-Meter Butterfly at the Olympic Games
Sandra Johnson was a competitive swimmer for more than 15 years before she began coaching. She is a longtime Olympic fan, and while working for the United States Olympic Committee in Colorado Springs, Colo., she had the opportunity to immerse herself in the Olympic Movement. Follow her on Twitter: @SandraJohnson46
