Tokyo 2020: Swimming-Australia's McKeown wins 100m backstroke gold in debut Olympics

Kaylee McKeown of Australia powered to her first Olympic gold medal on Tuesday after a stunning fightback in the women's 100m backstroke that was within a fingertip of her own world record.

Canada's Kylie Masse took a good lead from the start and held it at the halfway mark but McKeown switched gears out of the turn and clawed back to win in 57.47.

Masse won silver in 57.72 and Reagan Smith of the United States was third in 58.05.

The 20-year-old McKeown's time was just two hundredths of a second shy of the world record she set in the Australian trials in June.

Driven by the memory of her late father, the gold medal extends an impressive run of form this year that made McKeown the top ranked swimmer in three events in Tokyo, though she had to withdraw from one due to a tight schedule.

"It's not necessarily what I have been through, everyone has their own journey. It just so happens I have had a tough time," she said when asked about her preparations.

"My legs were definitely hurting in the last 20 metres ... I'm just thankful that I have come away with the position I have."