LONDON — Matt Grevers of the United States set an Olympic record to win the men’s 100-meter backstroke at the London Olympics on Monday.

Grevers finished in 52.16 seconds, 0.38 ahead of the previous mark set by fellow American Aaron Peirsol at the 2008 Beijing Games.

Nick Thoman, another American, was second in 52.92, and Ryosuke Irie of Japan was third in 52.97.