(AFP) - A "super-happy" Aryna Sabalenka surged past China`s Bai Zhuoxuan into the Australian Open third round on Wednesday ahead of fellow world number one Carlos Alcaraz resuming his quest for tennis history.

Three-time finalist Daniil Medvedev is also in action at a cooler and overcast Melbourne Park after days of hot weather, as are third seeds Coco Gauff and Alexander Zverev.

Four-time major winner Sabalenka raced 5-0 clear of qualifier Bai, ranked a lowly 702, on Rod Laver Arena before wobbling to give the Chinese player a glimmer of hope.

But the top seed quickly snuffed it out to race home 6-3, 6-1 and set up a clash next against either Britain`s 2021 US Open champion Emma Raducanu or Russian-born Anastasia Potapova, now representing Austria.

"Super-happy to close the (first) set, it gives me confidence that my game is there, my focus is there," said the Belarusian, who is bidding for a third Australian Open title in four years.

"Step by step. Super-happy with my win. There is always a little gap to improve."

Sabalenka has dropped just nine games so far as she looks to make amends for her upset in last year`s final to Madison Keys.

Ukrainian 12th seed Elina Svitolina and Turkish prospect Zeynep Sonmez were also early winners on day four, both sweeping past their opponents in straight sets.

On the men`s side, American Tommy Paul and Argentina`s Francisco Cerundolo safely negotiated the second round.

Alcaraz started his bid for a career Grand Slam with a three-set defeat of home hope Adam Walton and faces hard-hitting German Yannick Hanfmann later Wednesday.

The Spanish superstar Alcaraz already has six major titles aged 22 but success on the Melbourne Park hardcourts remains a glaring hole in his resume.

He has not made it past the quarter-finals in four trips to Australia.

If he does complete the career Grand Slam of all four majors he will be the youngest man to do it.

"I just really want to perform better than I did previous years," said Alcaraz.

"So I just feel this year probably it is one of those years that I will be able to, or will have the chance, to go further."

- Medvedev vows to stay positive -

The unpredictable Medvedev, runner-up in 2021, 2022 and 2024, is trying to keep his emotions in check this year and will again be put to the test against Frenchman Quentin Halys.

Gauff takes on Venus Williams` conqueror Olga Danilovic of Serbia after a straight-sets first-round win as she looks to improve on her best performance in Melbourne, which was a semi-final in 2024.

Zverev is in action in an evening match against France`s Alexandre Muller, the latest challenge in the German`s decade-long quest for a first Grand Slam title.

The world number three, runner-up last year to Jannik Sinner, dropped a set in his opening clash but said it was good to be stretched early in the tournament.

"It`s a positive for sure," he said.

"Because you have been tested and you know where you are and you know where your level is at, especially in difficult moments."

Home hopes dominate the evening action on centre court with sixth seed Alex de Minaur facing Serbia`s Hamad Medjedovic before Priscilla Hon meets American Iva Jovic.