USA's Caeleb Dressel celebrates winning to take gold in the final of the men's 100m freestyle swimming event during the Tokyo 2020 Olympic Games at the Tokyo Aquatics Centre in Tokyo on July 29, 2021. (JONATHAN NACKSTRAND / AFP)

TOKYO - American Caeleb Dressel set an Olympic record to win gold by a fingertip in the men's 100 metres freestyle in Tokyo on Thursday, denying Rio champion Australian Kyle Chalmers a second successive title.

It was Caeleb Dressel's second gold in Tokyo after the 4x100 freestyle relay win earlier this week

Dressel set the pace down the first 50, with Chalmers and Russian Kliment Kolesnikov close behind, then fended off a thrilling late charge from the Australian to cling on for the gold in 47.02.

Chalmers turned third at the halfway mark and was pulling back stroke for stroke but left his fightback too late, taking the silver just six hundredths behind, with Kolesnikov winning bronze with 47.44.

The Olympic gold was Dressel's fourth overall but his first in an individual event.

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"I wasn't worried about anything at all," he said when asked about the close contest.

"It means a lot. I knew the weight was on my shoulders."

It was the American's second gold in Tokyo after the 4x100 freestyle relay win earlier this week.

He said the victory in the individual event was sweeter.

"It is different and I know that now," he said.

"I didn't want to admit it. But it's up to yourself, there's no one to bail you out."