* Murray, Williams, Azarenka through
* Temperature reaches 40 degrees C
* Date-Krumm wins again
Andy Murray and Serena Williams steamrollered into the third round of the Australian Open on Thursday as sweltering heat at Melbourne Park failed to prove a leveller on day four of the year's first grand slam.
Suncream, hats and icepacks were the order of the day and spectators cooled off under misting fans as the temperature hit the 40 degrees Celsius mark in late afternoon.
Third seed Williams did her best to keep her time on court to a minimum as she swept aside Garbine Muguruza 6-2 6-0 before Murray, her counterpart in the men's draw, kept his cool to despatch Joao Sousa 6-2 6-2 6-4 on Hisense Arena.
Victoria Azarenka may be the defending champion and world number one but Williams is odds-on favourite to capture a 16th grand slam title and a sixth in Australia next week.
The Belarussian proceeded easily enough with a 6-1 6-0 thrashing of Eleni Daniilidou but any hopes she had that Williams, against whom she has a 1-11 record, might be hampered by the ankle she injured on Tuesday were quickly dashed.
The American split her lip with her own racket during the first set against her lowly-ranked opponent, but was barely troubled thereafter and set up a meeting with Japan's Ayumi Morita with her 10th ace of the match.
"I didn't feel anything today," the 31-year-old said of the ankle injury. "Obviously when you go out to play you're heavy on adrenaline and you're really pumped up.
"Usually I feel injuries after the match, but so far, so good. I felt much better than I ever dreamed of expecting to feel.
"I'm on the up and up. It can only get better from here."
The outer courts were again the place to go for upsets with Lithuanian Ricardas Berankis hammering 25th seed Florian Mayer 6-2 6-3 6-1 on court six, while women's 21st seed Varvara Lepchenko was a 6-4 6-2 victim of Elena Vesnina on court two.
Jo-Wilfried Tsonga looked to be wilting in the sweltering heat of Margaret Court Arena when Go Soeda was 5-3 up and serving for the second set but the seventh seed recovered to slap down the Japanese 6-3 7-6 6-3.
There were also wins for seeds Marin Cilic, Gilles Simon, Milos Raonic, Andreas Seppi and Philipp Kohlschreiber.
Kimiko Date-Krumm, the women's world number 100, continued her fairytale run some 23 years after making her Australian Open debut with a victory over a player 17 years her junior.
The 42-year-old Japanese is fast becoming a cult hero at Melbourne Park and emerged a 6-2 7-5 winner over Shahar Peer of Israel after 92 minutes of exertion on court six.
"It's not easy, not easy," she said. "I need a new body."
Former world number one Caroline Wozniacki was also feeling her age after her encounter with Croatian teenager Donna Vekic, which she won 6-1 6-4.
"I've been out here for a few years now and I feel like a veteran. Particularly when I'm playing against a 16-year-old," she said.
"I'm seriously starting to feel old and I'm 22! I got asked a few months ago if I was going to retire."
Berankis's victory means he will be Murray's next opponent and the convincing nature of his win over Mayer indicated that he might prove trickier for the Scot than Sousa.
Murray, 25, used all the weapons in his armoury in the 101-minute contest and every one of them was superior to that possessed by his Portuguese opponent.
The U.S. Open champion stuttered a little as he looked to close out the win but fired down his 14th ace to bring up match point before clinching the victory when a Sousa return went long.
"You need to get in control of the points and dictate them because otherwise you will get very tired very quickly in these conditions," Murray said.
Second seed Roger Federer opens the evening session on Rod Laver Arena against former top five player Nicolay Davydenko to decide who will meet Australia's last hope, Bernard Tomic, in the third round.
Tomic blew seven match points in his clash with Daniel Brands but sealed a 6-7 7-5 7-6 7-6 victory with the eighth - only the second time in 18 encounters on the main showcourt this week that a match was not won in straight sets.
Matches involving the top women have been particularly lop-sided and the first four seeds have yet to drop a set between them.
"I think I honestly can only speak for myself, but it seems like everybody is in great form, and it's going to be very interesting," said Azarenka.