The 30-year-old Serb will play Spain's Albert Ramos-Vinolas in the third round.
"Have been very, very tough conditions yesterday and today", said the top-ranked Nadal, who played at night on Friday after the temperatures had dropped.
"It's the beginning of the season".
Monfils, who called Thursday's conditions the toughest he's ever played in, had only these words for his peers scheduled to play Friday.
I think this limit should be a little lower because playing in this condition is not nice for anyone'.
"It was right at the limit", Djokovic said.
Cornet's woes during her 7-5, 6-4 loss to Mertens came the day after countryman Gael Molfils confessed he thought he was going to collapse during a loss to Novak Djokovic. I mean, outside Grand Slams, ATP is obviously not behind Grand Slams (which are International Tennis Federation events). Obviously he wasn't at his best, he was exhausted at the end of the second and third sets, the fourth could have gone either way really. "It was about just hanging in there and try to use every opportunity".
Few tennis fans will be complaining about Novak Djokovic being back on the court following a six-month injury layoff stretching back to last July. "I had a lot of faith, self-belief and I know what I am capable of", Djokovic added.
"It was really hard to play", del Potro said.
"It was tough to breathe". This didn't happen too many times in my career that I have maybe some tension in the muscles or whatever, some kind of physical challenges.
"I trained this winter in Miami". Nor did Wimbledon champion and No. 3 Garbine Muguruza.
"I'm telling you I was dying on the court for 40 minutes".
But they were not deemed extreme enough for the tournament to implement its policy, which can see matches on open courts postponed and those on the show courts played with the roof closed.
The Swiss defending champion headlines Rod Laver Arena in the evening, with the 19-time Grand Slam victor tackling France's Richard Gasquet.
"These seats are hot; they are burning, and if you touch them it feels like your clothes are on fire", said Marintelli, whose discolored nose was in clear need of some ointment. "My feet are burning".
Maria Sharapova was untroubled by the heat, although she was on court in the morning and avoided the worst of it.
"I think it is a health issue", Nadal said. I tried to cool down, but even with ice towel, the water [I could not].
Fifth seed Thiem took the advice to heart as he struggled through a energy-sapping five-setter against Denis Kudla. It's fine. I finished the match.