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MELBOURNE Jan 14 (Reuters) - Rafa Nadal got a free pass into the second round of the Australian Open when Bernard Tomic retired injured on Tuesday, a welcome reprieve from stifling heat that led one player to describe conditions at Melbourne Park as "inhumane".
Australian Tomic, booed off Rod Laver Arena by his compatriots, blamed a groin injury for withdrawing having lost the opening set 6-4, leaving top seed Nadal to join fellow "Big Four" players Roger Federer and Andy Murray in securing his passage.
Defending champion Victoria Azarenka led third seed Maria Sharapova and former world number one Caroline Wozniacki over the first hurdle in the women's draw, but there was only one topic of conversation on day two of the championships.
"Every single person that I saw coming in from practice or going out to play a match or coming back from a match, everyone just said like, 'It's really hot today'," Murray told reporters after beating Go Soeda 6-1 6-1 6-3.
Azarenka said being on court was like "dancing in a frying pan" and Wozniacki thought her water bottle was going to melt, but for some players the impact of the extreme heat, forecast to continue until Friday, was more serious.
Frank Dancevic slammed organisers for forcing players to compete in "dangerous" conditions after he collapsed on court and passed out for a minute in his match on one of the more exposed outer courts.
"I think it's inhumane, I don't think it's fair to anybody, to the players, to the fans, to the sport, when you see players pulling out of matches, passing out," the Canadian told reporters after his defeat to Benoit Paire.
"I've played five-set matches all my life and being out there for a set and a half and passing out with heatstroke, it's not normal.
"Until somebody dies, they're just keep going on with it and putting matches on in this heat."
A ballboy also fainted, while China's Peng Shuai said the heat had caused her to cramp up and vomit and she had to be helped from the court after her 7-5 4-6 6-3 defeat to Japan's Kurumi Nara.
Organisers said temperatures peaked at 42.2 degrees Celsius (108 degrees Fahrenheit) in the early evening but, taking into account the low humidity, the threshold for calling off play had not been reached.
"There were a few players who experienced heat-related illness or discomfort, but none required significant medical intervention after they had completed their match," said tournament doctor Tim Wood.
Federer, watched by the newest member of his coaching team, Stefan Edberg, kept his usual cool in the hot conditions and eased into the second round with a 6-4 6-4 6-2 drubbing of local wildcard James Duckworth.
"It can become just a very mental thing and you just can't accept that it's hot," the 17-times grand slam champion said of coping with the conditions.
"Just deal with it, because it's the same for both. That's basically it."
Wimbledon champion Murray had other things on his mind besides the weather and was clearly delighted with his clinical victory over Saeda in just his third competitive match since returning from four months on the sidelines after back surgery.
"I maybe didn't expect to play as well as I did today, but the signs have been good in practice," the fourth seed said. "I started the match off very well and did everything solid."
Juan Martin Del Potro, the fifth seed, had considerably more difficulty with his first-round opponent, and needed more than three hours to get past American qualifier Rhyne Williams 6-7(1) 6-3 6-4 6-4.
That Lleyton Hewitt was involved in one of the longest matches of the day surprised no one, but the former world number one ended up a 7-6(4) 6-3 5-7 5-7 7-5 loser to Italian Andreas Seppi despite coming back from two sets down to hold a match point.
Azarenka made a stuttering start to her bid for a third straight title when Swede Johanna Larsson kept her out in the sun for 106 minutes before succumbing 7-6(2) 6-2 in the first match on Rod Laver Arena.
Former Melbourne Park champion Sharapova, also on the comeback trail after a shoulder injury, took on American Bethanie Mattek-Sands in the final match of the day on the main showcourt.
Mattek-Sands retained her distinctive knee socks, and Sharapova's progress was not as slick as her own sleek dress, but the Russian wrapped up a 6-3 6-4 victory in one hour 39 minutes.
Tomic's retirement, one of nine in the first round, left Nadal with less time on court than he would have liked, but the Spaniard said he would not be training any harder on Wednesday to compensate.
"Days like today, tomorrow that will be very hot, it's better to save little bit of energy," he said.
(Editing by Stephen Wood)