The two-time world champion touched in 49.45s to better his own world best 49.50s set at the 2019 World Championships.

Hungarian 200m fly champion Kristof Milak was second in 49.68s – only the fourth man ever to go under 50 seconds – and Noe Ponti of Switzerland third in 50.74s.

Dressel was always the man to beat, having set the third fastest time ever in the heats with no other active swimmer before the final close to his world record.

It was the fourth new world record in the Tokyo pool, and the second individual one after South Africa’s Tatjana Schoenmaker crushed the long-standing 200m breaststroke mark yesterday.

Australia’s women set a new benchmark in the 4x100m relay, as did China in the women’s 4x200m relay.

Dressel remains on track for possible six gold medals, having already won the 100m freestyle crown and helped the US team clinch the 4x100m relay title.

He is expected to later today contest the 4x100m mixed medley relay final and is the undisputed favourite in the 50m freestyle final tomorrow.

Dressel is also expected to swim the 4x100m men’s medley relay tomorrow, the final event in the Tokyo pool.