Australia’s gold-medal favourites Kaylee McKeown and Ariarne Titmus have landed early blows in their swimming duels with feted world rivals at the Tokyo Olympics.

McKeown punched out an Olympic record in an extraordinary show of brinksmanship with her 100-metre backstroke foes on Sunday night.

The Australian world-record holder has two chief rivals: Canada’s reigning world champion Kylie Masse and American Regan Smith.

Masse set an Olympic record in her heat and, minutes later, Smith bettered that.

Titmus controlled the field in the 400m free, with a calm and comfortable swim touching in 4:01.66.

After a huge 18 months, Tamsin Cook made her return to international swimming with a time of 4:04.80 👏#TokyoTogether | #Tokyo2020 | #Swimming | @AUSOlympicTeam pic.twitter.com/wNQu2rztt5

— Australian Swim Team (@DolphinsAUS) July 25, 2021

The 20-year-old McKeown, showing nerves of steel on Olympic debut, eclipsed them both with a fresh Games benchmark of 57.88 seconds – just 0.43 seconds from her world record.

McKeown’s 29-year-old teammate Emily Seebohm marked her fourth Olympics with a 58.86 to be fifth quickest into Monday’s semi-finals.

And 20-year-old Titmus booked a duel of the pool at the Tokyo Games: A 400m freestyle showdown with American great Katie Ledecky.

Ledecky, a five-time Olympic champion rated the best female swimmer ever, was quickest into Monday’s mouth-watering 400m freestyle final.

But Titmus eased to victory in her heat and was still third fastest behind Ledecky and China’s Bingjie Li.

What a night! Now get ready to back it up tomorrow 💪

Tomorrow's finals:
💚Emma McKeon | 100m fly | 11:30am
💛Ariarne Titmus | 400m Free | 12:20pm
💚Men's 4x100m free relay | 1:05pm#TokyoTogether | #Tokyo2020 | #Swimming | @AUSOlympicTeam pic.twitter.com/qrT7Po8zsx

— Australian Swim Team (@DolphinsAUS) July 25, 2021

In the men’s 200m freestyle, Australia’s Thomas Neill won his heat and was eighth fastest into the semi-finals but Elijah Winnington struggled again, finishing seventh.

Winnington also placed seventh earlier on Sunday in the 400m freestyle final.

Stalwart Mitch Larkin produced a solid heat swim to be fourth fastest into the 100m backstroke semi-finals, with teammate Isaac Cooper through in 13th spot.

And Chelsea Hodges advanced to 200m breaststroke semis but teammate Jess Hansen didn’t progres from the heats.

https://twitter.com/7olympics/status/1419250161637789698

Australia’s men’s 4x100m freestyle relay team qualified third fastest behind Italy and the United States for Monday’s final, capping a successful day at the pool.

In Sunday morning’s finals, Australia’s women’s 4x100m freestyle relayers won gold – the nation’s first of the Tokyo Games.

Sisters Cate and Bronte Campbell, Emma McKeon and 19-year-old Meg Harris set a world record to win.

Australia’s Jack McLoughlin claimed silver in the 400m freestyle while Brendon Smith, on his first senior swim team, took bronze in the 400m individual medley.

-AAP