Local favourite and sixth seed Sam Stosur became the highest ranked player to crash out of the Australian Open first round on Tuesday while men's fourth seed Andy Murray was pushed by Ryan Harrison before he overcame the American teenager in four sets.

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Petra Kvitova, Maria Sharapova and Novak Djokovic, however, had all ensured they spent as little time as possible in the heat with lopsided victories as temperatures in Melbourne soared for the second successive day.

US Open champion Stosur, however, was unable to withstand the pressure cooker environment on Rod Laver Arena in front of local fans holding heightened expectations as she crashed to a 7-6, 6-3 loss to Romania's Sorana Cirstea.

"I really, really wanted to do well here and over the (Australian) summer," Stosur said.

"I did everything I could to try and give myself a good opportunity.

"It obviously didn't happen (and) it's not through lack of trying or not wanting it or anything like that. I mean, you can't pick the times that you want to play well.

"That's sport."

Murray was also in danger of following Stosur after he lost the first set to Harrison, before he rallied to win their three hour, 12 minute encounter 4-6, 6-3, 6-4, 6-2.

The 24-year-old Murray also caused some concerns for his large fan base on Hisense Arena when he clutched at his right hamstring in the second set, while he also seemed to jar his right ankle in the final set shortly before he sealed victory.

Earlier, World No. 2 Kvitova, who beat Sharapova last year at Wimbledon to claim her first grand slam title, was unruffled by the hot conditions in a ruthlessly efficient 6-2, 6-0 victory over Vera Dushevina taking a tick over one hour.

Kim Clijsters and Martion Bartoli recorded 6-0, 6-0 victories over Dinara Safina and Italy's Tathiana Garbin respectively last year at Melbourne Park.

Fourth seed Sharapova, however, was as merciless on the second show court on Hisense Arena, beating Argentina's Gisela Dulko 6-0, 6-1 in 58 minutes.

Djokovic's victory in Melbourne last year sparked a remarkable 12 months in which he won three grand slam titles and compiled a 70-6 record as he finally overhauled Rafa Nadal and Roger Federer as the best player in men's tennis.

The Serb began his title defence in style at the year's first grand slam tournament with an emphatic 6-2, 6-0, 6-0 victory over Italian journeyman Paolo Lorenzi.

He had stumbled early with a break to trail 2-1 but rattled off 17 successive games to seal the match in 92 minutes.

"It took me a couple games to get into the right rhythm," Djokovic said. "You know, it's a bit difficult conditions.

"I think it was really the hottest day since I've arrived here, so trying to get used to that. But I think I played well after the first set was finished."

Fifth seed David Ferrer, a beaten semi-finalist last year and champion in Auckland last week, also spent as little time in the blazing sunshine as possible.

The Spaniard took just one hour 44 minutes to blitz Portugal's Rui Machado 6-1, 6-4, 6-2 and progress to the second round.

A rusty and agitated Serena Williams returned to Melbourne Park after a two-year break with a scratchy 6-3, 6-2 win over Austria's Tamira Paszek on Tuesday.

Williams, unable to defend her 2009 and 2010 titles last year due to a freak foot injury, entered Rod Laver Arena with only two matches under her belt in five months.

The lack of match practice showed for much of the 79-minute contest against the feisty Wimbledon quarter-finalist.

The win was the 13-times grand slam champion's 15th in a row at the year's first grand slam. She faces Czech Barbora Zahlavova Strycova in the second round.