Victoria Azarenka felt like she was "dancing in a frying pan" but the defending champion managed to avoid jumping into the fire at the Australian Open.
Heat was the story of the second day as temperatures soared over 42C at Melbourne Park, leading to one player fainting, two others pulling out with heat exhaustion and another vomiting on court, while plenty of fans stayed away.
Azarenka, the champion for the last two years, avoided the worst of it by playing in the first match against Johanna Larsson of Sweden, but for a while the second seed looked to be in trouble before coming through 7-6 (7/2) 6-2.
Larsson twice served for the first set only for Azarenka to break back and then win the tie-break convincingly.
The Belorussian said: "It wasn't too bad. I went to practise after so I'm okay.
"It's not easy those conditions but it's the same for everybody. You just have to adapt to it and try to do the best things to prepare. Actually I felt better as the match was going on than in the beginning."
Third seed Maria Sharapova had the best of the scheduling, playing Bethanie Mattek-Sands of the USA in the night session on Rod Laver Arena.
It was the Russian's first grand slam match since Wimbledon after she missed the US Open because of shoulder problems that brought an early end to her season.
Mattek-Sands lost the first four games but fought back well and it was tighter than the 6-3 6-4 scoreline indicated.
Sharapova said: "I was happy just to play, despite the heat or anything. I've been out of the game for a while so I was happy to be back in a grand slam atmosphere."
Tenth seed Caroline Wozniacki dropped only two games in defeating Spain's Lourdes Dominguez Lino 6-0 6-2.
She said of the conditions: "It was a little warm out there today. I put a (drink) bottle down on the court and it started melting a little bit underneath. It was great that I managed to finish it off in two sets and it wasn't too long."
Wozniacki is playing in her first grand slam since becoming engaged to golfer Rory McIlroy but insists she is as hungry as ever to try to be a grand slam force once more.
The 23-year-old has not reached the quarter-finals at one of the sport's four biggest tournaments for two years.
She said: "I think I'm in a very good place in my life right now, on the court and off the court. I know what I want. I want to improve all the time. I want to be the best."
Fifth seed Agnieszka Radwanska won the first set to love against young Kazakh Yulia Putintseva but thereafter found herself in a real battle before coming through 6-0 5-7 6-2.
There was a scare for eighth seed Jelena Jankovic when she fell during her match against Japan's Misaki Doi and needed treatment to her ankle but she recovered to win 6-1 6-2.
Sloane Stephens, who sensationally beat Serena Williams in the quarter-finals last year, trailed Yaroslava Shvedova 5-1 before fighting back to win 7-6 (7/1) 6-3.
Williams is back in action on Wednesday when she meets Serbia's Vesna Dolonc in the second round while the most intriguing clash sees fourth seed Li Na take on 16-year-old Swiss Belinda Bencic on Rod Laver Arena.