15 greatest upsets in Summer Olympic history

4. 1964: Billy Mills shocks the world

Not many people knew who Billy Mills was heading into the 1964 Summer Olympics in Tokyo. By the time he crossed the finish line of the 10,000m race, his upset victory would become the stuff of legend.

The 1964 10,000m race featured 29 runners, including Australian Ron Clarke, who was the world record holder. Mills, who ran track in college at Kansas, grew up on an Indian Reservation in South Dakota. With his win in the race, Mills became only the second Native American (Jim Thorpe) to win an Olympic gold medal.

The drama unfolded at the end of the race, when Tunisia’s Mohammed Gammoudi ran between Clarke and Mills to take the lead. Clarke then began to close the gap on Gammoudi, with Mills running third. Suddenly, Mills kicked it into another gear, racing past both Clarke and Gammoudi to win the race by 100m.

With his win, Mills became the first American to win the event, and he still is to this day. In fact, the closest an American has come to winning was in 2012, when Galen Rupp took the silver. His time of 28:24.4 set an Olympic record for the event. In 1984, Mills was elected to the U.S. Olympic Hall of Fame for his accomplishments in track.

Next: 3. 2000: Gardner takes down the 'Russian Bear'