Reigning women's champion Naomi Osaka and top seed Ashleigh Barty are on course for a potential fourth-round showdown as they picked up wins in their respective second-round matches in the Australian Open Wednesday.

On the men's front, Rafael Nadal ramped up his march toward an unprecedented men's 21st Grand Slam crown but needed five match points to put away tenacious qualifier Yannick Hanfmann.

The impressive Barty, chasing a first title at her home Slam, barely broke sweat as she breezed past Italian qualifier Lucia Bronzetti 6-1, 6-1 in just 52 minutes in the heat of Rod Laver Arena in their second-round encounter.

Not to be outdone, defending champion Osaka rushed through the first set 6-0 against Madison Brengle but then had a couple of dicey moments in the second set, before polishing it off 6-4, greeting the beaten American with a smile at the net.

Rivals Barty and Osaka, who share six major titles between them, are now one victory away from a last-16 showdown at Melbourne Park.

But first Barty, the Wimbledon champion and hot favorite in Melbourne, faces a potentially tricky task against 30th seed Camila Giorgi.

"She is an incredible ball striker and one of the most athletic girls out there," said the world No. 1 of the experienced Italian.

The ultra-consistent Barty, who won the title at a lead-up tournament in Adelaide, hasn't dropped her serve for 48 straight games over five matches this year.

Japan's Osaka faces American Amanda Anisimova, who sprang a shock in defeating Olympic champion Belinda Bencic.

Osaka, the winner of the 2019 and 2021 Australian Opens, has vowed to have more fun on court this year, following a difficult last year in which she said she had suffered depression.

"I am a bit of a perfectionist. I feel that if I compare myself to the past I will never be satisfied," she said, to cheers from the crowd.

In-form eighth seed Paula Badosa, who won the Sydney warm-up tournament, and French Open champion Barbora Krejcikova both sailed through to round three in two sets.

Nadal quest for 21

With defending men's champion Novak Djokovic deported on the eve of the season's first Grand Slam, the men's draw has opened up for Spanish veteran Nadal.

The 20-time Slam winner, who recently won his first tournament after five months out battling a foot injury, was never really troubled by the German Hanfmann until the end of the third set.

Down 3-5, 0-40, the world No. 126 fought back to extend the contest and saved two more match points, before finally succumbing 6-2, 6-3, 6-4.

Next up for the 35-year-old Nadal is Russian 28th seed Karen Khachanov, which should be an altogether bigger test of his title credentials.

Nadal, the sixth seed, could face third seed Alexander Zverev in the quarterfinals but he is refusing to look that far ahead.

"I don't know, I am in the third round, I need to win very tough matches to be there," the Spanish great said.

"I never think that far. You can imagine now less than ever, no?" he added, an apparent nod to his recent injury struggles. Nadal also had COVID-19 last month.

Olympic champion Zverev later plays Australia's John Millman, who will garner plenty of partisan vocal support in a late-night encounter on Rod Laver Arena.

Seventh seed Matteo Berrettini, who endured frequent lavatory trips in a gutsy four-set win Monday, defeated American Stefan Kozlov and plays teenage 31st seed Carlos Alcaraz.

Also through, after surviving in five sets over Korean Kwon Soon-woo, was Canadian 14th seed Denis Shapovalov.

But Poland's 10th seed Hubert Hurkacz was a notable casualty at the hands of Frenchman Adrian Mannarino.