Fourth seed Murray was leading Andrei Pavel 6-2, 3-1 when the Romanian quit after 45 minutes with a back injury that had kept him out of the sport for most of last year.
"I guess if you want to do well in the tournament, it´s good to conserve some energy ... hopefully that was a good thing," the Briton said, weighing the pros and cons of his short outing in 37 degree Celsius heat. Next up for him is Marcel Granollers.
Serena Williams did not waste too much time either, cantering through with a 6-3, 6-2 win over China´s Yuan Meng. The American second seed is seeking a fourth Australian title after winning here in 2003, 2005 and 2007.
"It was a little hot for me today," she smiled, sipping a drink. "It was a case of taking my time, not giving 1,000 percent, you know?
"I was getting super thirsty out there -- at one stage I had to stop and have a drink of water," she laughed.
"It was definitely extreme conditions," she added, stifling a sniffle. "I do have a little bit of a head cold ... I hope that goes away."
Serena was joined in the second round by big sister Venus who enjoyed a 6-3, 6-3 victory over Germany´s Angelique Kerber.
Sixth seed Venus is still seeking a first singles title at Melbourne Park despite having five Wimbledon and two US Open crowns to her name.
World number four Elena Dementieva survived the scorching heat to see off Kristina Barrois. Unbeaten so far this year after picking up titles in Auckland and Sydney, Dementieva beat the German 7-6, 2-6, 6-1.
Polish ninth seed Agnieszka Radwanska was an early casualty, however, falling 7-6, 4-6, 6-1 to Ukraine´s Kateryna Bondarenko.
Former world number one Lleyton Hewitt suffered a drawn-out agonizing exit from his home grand slam when he was beaten 5-7, 6-2, 6-2, 3-6, 6-3 by Chilean 13th seed Fernando Gonzalez.
It was Hewitt´s first opening round defeat at the Australian Open since 2002, when he was suffering chicken pox.
Finalist at Melbourne Park four years ago, Hewitt slid down the rankings last year after undergoing hip surgery and only returned to competition this month.
"I´ll probably look back at it in a couple of days´ time, look at where I could have improved and whatever," Hewitt said.
Roger Federer had taken the first step toward his record-tying 14th Grand Slam title with a 6-1, 7-6 (7-4), 7-5 victory over Andreas Seppi in the late game Monday.
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