* Djokovic, Serena race into third round
* Dodig feared he would die in heat
* Li, Ferrer and Berdych also through
MELBOURNE, Jan 15 (Reuters) - Tournament favourites Novak Djokovic and Serena Williams raced into the third round of the Australian Open and out of the heat on Wednesday as controversy over play continuing in scorching temperatures rumbled on for a second day.
Cloud cover and a gusty wind helped keep temperatures just below the peak of 42.2 degrees Celsius they reached on Tuesday, when Canadian Frank Dancevic passed out and accused organisers of forcing players to play in "inhumane" conditions.
Ivan Dodig became the 10th player to retire in the first three days of the tournament, though, when he was unable to complete his match against Bosnian Damir Dzumhur on one of the exposed outer courts at Melbourne Park.
"Today, 30 minutes after the match I could not walk," Croatian Dodig told reporters. "There were 10 people around me. I was thinking I could maybe even die here.
"I think we deserve that somebody listens to the voice of the players."
Djokovic needed 107 minutes to take the second step on the path he hopes will take him to a fourth successive title by thrashing Argentine Leonardo Mayer 6-0 6-4 6-4 on Rod Laver Arena.
Williams also hot-footed it into the third round with a one-sided 6-1 6-2 demolition of Vesna Dolonc before revealing her own particular visualisation technique for keeping cool.
"I just pretend I'm in Hawaii riding a wave, that's all I can do," she said after setting up an encounter with Slovakia's Daniela Hantuchova who survived a gruelling battle against Karolina Pliskova, winning 12-10 in the deciding set.
Djokovic retired from a match against Andy Roddick in another Melbourne heatwave five years ago but proved against Mayer that he is an altogether stronger player than in 2009.
"You don't want to spend too much time in the heat. You want to try to win as quick as possible," the second seed, who next faces Denis Istomin, told reporters.
"I prepared myself mentally for that. It's not just physically. Mentally you need to be tough enough to not give up and not think about what conditions can do to you."
World number one Williams was her usual mix of elegance in her dress and brutality in her play as she dismissed Dolonc in just over an hour on the same court.
Though no one could ever doubt the mental strength of a player who has won 17 grand slam titles, Williams admitted to a sleepless night worrying about the impact the heat might have on her bid for a sixth Melbourne title.
"I kept waking up in the middle of the night last night, just paranoid," Williams told reporters.
"I just wanted to stay hydrated. The last thing I want to do is to cramp in this weather. It can happen so easy. I was just drinking a tremendous amount of water."
Williams has seen off at least a couple of generations of younger women looking to knock her off the top of the game and 16-year-old Swiss Belinda Bencic is tipped to be in the vanguard of the next wave.
The qualifier, coached by the mother of Martina Hingis, started poorly in her match against Chinese fourth seed Li Na but after losing the first seven games, rallied to force the second set into a tiebreak before losing 6-0 7-6 (5).
Two former grand slam champions who have dropped out of the top 10, Ana Ivanovic and Samantha Stosur, had straightforward two-set victories to set up a third round meeting on Friday, when temperatures could hit 44 degrees Celsius.
"I think there's got to be some common sense," Australian Stosur said. "Because you don't want it to get dangerous and have somebody getting hurt because of it."
Seventh seeded Czech Tomas Berdych, dressed in what looked like a blue and white striped Argentina soccer shirt was the first man into the third round when he hammered Frenchman Kenny De Schepper 6-4 6-1 6-3.
Berdych said conditions were the hottest he had played in and suggested that if the threshold for stopping matches had not been reached, it was probably set too high.
France's Richard Gasquet soon joined Berdych by beating Russian Nikolay Davydenko 7-6 (7-3) 6-4 6-4 in match that featured a candidate for point of the tournament.
Davydenko looked to have clinched it with a no-look underarm shot from behind the baseline only for ninth seed Gasquet to hit an outrageous winner over his shoulder running back into the court away from the net.
Third seed David Ferrer continued his progress through a section of the draw further weakened by the 6-4 3-6 6-3 3-6 6-3 defeat of 14th seed Mikhail Youzhny at the hands of Florian Mayer on Wednesday.
Ferrer's unrelenting fighting spirit put him in good stead in his match over Frenchman Adrian Mannarino, who won the second set before wilting in the heat and going down 7-6 (7-2) 5-7 6-0 6-3.
World number eight Stan Wawrinka, playing in the relative cool of the evening on Margaret Court Arena, also needed four sets to get past Alejandro Falla 6-3 6-3 6-7 (7-4) 6-4. (Editing by John O'Brien and Martyn Herman)