RIO DE JANEIRO (REUTERS) - Adam Peaty demolished his own world record in the heats of the 100 metres breaststroke on Saturday (Aug 6) as he launched his bid to become the first British man to win an Olympic swimming gold medal for 28 years.

Peaty set a new mark of 57.55 seconds - cutting 0.37 from his previous record, set in London last year - and said he hoped to shave off some more in Saturday evening's semi-finals.

"Going down that first 50, I knew it was fast, and I knew I turned fast. It wasn't until 25m to go, the crowd started to roar and it was like, there's no Brazilians in this race and they've got to be shouting for something," Peaty told reporters.

"Hopefully, tonight I'm going to feel a little bit better and swim a little bit faster... We're going to keep pushing the boundary."

World champion Peaty, swimming at his first Olympics, is seeking to become the first British male swimmer to win Olympic gold since Adrian Moorhouse in 1988, six years before he was born.