Adam Peaty of Britain has become the first man to go under 57 seconds in the 100-meter breaststroke at the world swimming championships.

He won his semifinal heat in 56.88 seconds on Sunday night, bettering his old world record of 57.10 set last August in Glasgow, Scotland.

Peaty is seeking his third straight world title in the event. He also won the 100 breast at the 2016 Rio de Janeiro Olympics.

The final is Monday night.