The thermometer edged towards 40C in the shade as Djokovic and opponent Gael Monfils took to a sun-baked Rod Laver Arena for their second-round match, which the six-time champion eventually won 4-6 6-3 6-1 6-3.
The crowd sang "Happy Birthday" and gave three hoorays to celebrate Kerber's 30th birthday. I was trying from the first point to be aggressive, but also staying really focused on my game, playing every single point.
Federer's Swiss colleague, Stan Wawrinka, also had the benefit of an evening match but the 2014 champion was beaten 6-2, 6-1, 6-4 by the American Tennys Sandgren in the final match in Margaret Court Arena.
Six-time Australian Open champion Novak Djokovic is finding his form, breaking serve five times to advance to the second week at Melbourne Park for the 11th time with a 6-2, 6-2, 6-3 victory over No. 21 seed Albert Ramos-Vinolas on Saturday.
"Lindsay is wonderful. We've had three years together and she has taught me how to handle big moments like this", said Keys, who made the Australian Open semis in 2015.
The maturing Australian 22-year-old dispatched French veteran Jo-Wilfried Tsonga in the last round and now faces third seed Dimitrov, who has struggled so far.
Monfils saved two more match points, the second with a superb crosscourt forehand, but Djokovic converted at the fourth attempt with a simple volley.
He added: The conditions were brutal, that's for sure.
It was the Latvian who ended her Grand Slam comeback in the last 16 of the US Open in 2017 as she returned from a drug ban.
"I did my job in two sets against someone that's been troubling in the past for me", Sharapova said.
"I think there are a lot of things I need to get better at and to improve on", Sharapova said.
Next up is 2016 Australian Open champion Angelique Kerber, who beat Donna Vekic in two easy sets.
"I don't want to take anything away from her and the way she played".
Muguruza acknowledged that the heat was bothersome, but it wasn't the hottest conditions she'd experienced in Australia.
No. 123-ranked Pera is making her Grand Slam debut and, after losing in the last round of qualifying, didn't even know she had a spot in the main draw until Margarita Gasparyan withdrew with an injury.
"I'm looking forward to playing against her", the German said. "I understand there is a factor of tickets".
Tournament director Craig Tiley defended the response of officials to the extreme heat on both Thursday and Friday, saying "we start the event with this set of rules and policies in place, and in the interest of fairness, can't change them halfway through".
American Madison Keys, a U.S. Open finalist a year ago, took just 41 minutes to beat Russian Ekaterina Alexandrova 6-0 6-1 in the second round.
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