Top seed Rafa Nadal was granted an easy passage into the second round of the Australian Open after his opponent Bernard Tomic retired hurt after losing the opening set of their match 6-4.
Australian Tomic was jeered by spectators at the Rod Laver Arena after he told Nadal he would no longer go on, having appeared uncomfortable with an apparent thigh injury.
Tomic left the court for a medical time-out for several minutes at the change of ends at 2-1 and later ripped a bandage off his high left thigh at the urging off his camp.
"I just want to say for Bernard, I hope he really gets better very soon," world number one Nadal said in the courtside interview.
Nadal will play Australian wildcard Thanasi Kokkinakis in the second round.
Meanwhile, Roger Federer's partnership with Stefan Edberg got off to a winning start as the Swiss made light of brutally hot conditions to reach the second round.
Edberg took part in his first training session at Melbourne Park on Monday after agreeing to coach Federer for ten weeks this year.
And there was nothing to worry about for the watching Swede, who somehow managed to look cool in the 40C heat, as Federer eased to a 6-4 6-4 6-2 victory over Australian wild card James Duckworth.
Edberg, who won six grand slam titles, was Federer's idol when he was growing up, but there were not too many glances from the sixth seed towards his support box during the match.
He said: "I realised after a set that I hadn't looked up once. I thought, 'I better check if he's actually sitting there'. He was wearing sunglasses. 'Okay, he is there'.
"I don't look up too much. I stopped doing that way back when because you just can't be dependent on these looks all the time. Being coached from the sidelines, that's not how I grew up.
"Clearly when I did look up, it's nice seeing him sitting there. Even if he wasn't my coach, it would be nice. Plus he's in my corner. It's great."
"Being coached from the sidelines, that's not how I grew up" - Roger Federer
Federer thinks dealing with the heat is more of a mental challenge than physical.
He said: "If you've trained hard enough your entire life, or just the last few weeks, and you believe you can come through it, there's no reason (you can't). If you can't deal with it, you throw in the towel."
Andy Murray's form matched the weather as he scorched into the second round with victory over Japan's Go Soeda.
It was just the fourth seed's third competitive match following back surgery in September but he took only an hour and 27 minutes to win 6-1 6-1 6-3.
The soaring temperature had been the main talking point on day two at Melbourne Park so to win so quickly was a major positive for the three-time runner-up.
Thirteenth seed John Isner did retire from his match but it was an ankle injury rather than the heat that put paid to the American's chances.
Isner surprised himself by winning the ATP Tour title in Auckland last week despite the problem but called it day trailing qualifier Martin Klizan 6-2 7-6 (8/6).
That section of the draw is now wide open after 21st seed Philipp Kohlschreiber pulled out before the start of play because of a hamstring problem.
One of those two had been expected to reach the fourth round, where they were seeded to meet world number four Murray.
Tenth seed Jo-Wilfried Tsonga was a comfortable 7-5 6-3 6-3 winner over Italy's Filippo Volandri while Japanese 16th seed Kei Nishikori needed a punishing three hours and 41 minutes to defeat Australian Marinko Matosevic in five sets.
Canadian Frank Dancevic was one of the worst victims of the heat, the qualifier collapsing on the court during his match against 27th seed Benoit Paire.
Remarkably, Dancevic carried on but unsurprisingly lost in straight sets.
Eleventh seed Milos Raonic and Grigor Dimitrov, seeded 22nd, both came through in four sets.