The second seeded Russian had a meltdown as the heat was turned up and had to dig deep to save two match points before staging an epic comeback to beat courageous compatriot Alexandra Panova 6-1, 4-6, 7-5.

British sixth seed Murray had a much easier time, cruising into the third round with a 6-1, 6-3, 6-2 drubbing of local hope Marinko Matosevic.

Other seeds progressing included men's seventh seed Tomas Berdych, 24th seed Richard Gasquet and women's 10th seed Ekaterina Makarova.

Roger Federer and Rafael Nadal, who share 31 Grand Slam titles between them, are in action later Wednesday, with world number ones Serena Williams and Novak Djokovic playing their second round matches on Thursday.

While the searing 42 Celsius (107.6 Fahrenheit) heat of last year has yet to materialise in Melbourne, temperatures reached 32 C and players, including Sharapova and Murray, draped ice towels around their shoulders at the changeovers.

At the 2014 tournament extreme heat forced organisers to suspend play for several hours following days of complaints about "inhumane" conditions which left some players fainting and vomiting.

Sharapova, who can unseat Serena Williams as world number one if she wins the title, wilted badly after winning the opening set, firing a slew of unforced errors that almost saw her on an early plane home.

"I didn't actually want to be out here for two-and-a-half hours but that's sometimes the way it goes on days when you're not playing your best -- sometimes it's good enough just to get through," she said.

"I was one point away from being out of this tournament twice today and not playing my best tennis so I'm just happy I was able to win that last point."

Out of the blocks -

The five-time Grand Slam champion, red-faced from the heat, went down 4-1 in the deciding set and looked out for the count, but rallied to save two match points when down 4-5.

Panova, a qualifier, kept pressing but the world number two had the bit between her teeth and used her considerable experience to hang on and set up a third round tie against either Slovak Anna Schmiedlova or Kazak Zarina Diyas.

In contrast Murray, a three-time Australian Open runner-up, was always in charge against Matosevic, continuing his dominant record against Australians, having now won all 10 previous Tour level meetings with Australian players.

The Scot jumped out of the blocks and wrapped up the opening set in just 21 minutes but had some tighter games in the second and third sets, breaking his opponent's serve seven times on Margaret Court Arena.

He will next face Portugal's Joao Sousa, who beat 32nd seeded Martin Klizan after the Slovak retired midway through their game.

"I started the match extremely well and Marinko was a bit slow at the beginning and he improved as the match went on and there was a lot of tight games in the second and third sets," said Murray, a two-time Grand Slam champion.

Second seed Federer, aiming for an 18th major title, meets later Wednesday with Simone Bolelli, who is yet to beat a top 10 player in 34 attempts, while third seed Nadal faces qualifier Tim Smyczek.

The Spaniard has never lost to a qualifier at a major tournament.

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