NOVAK DJOKOVIC outlasted French-fried Gael Monfils in brutal conditions as the court surface temperature reached 69C.
Monfils said he "was dying on court for 40 minutes" and even nicked a ballboy's water in a desperate bid to keep cool.
Monfils said conditions were "risky" and when told the air temperature is set to RISE from the high 30s C to 42C on Friday, added: "Honestly, good luck for the guys."
The Frenchman refused to slam umpire John Blom and tournament officials but felt they should have relaxed rules by allowing more time between points and sets – Djokovic even received a warning at one point.
Monfils said: "I train this winter in Miami. Was pretty hot. I thought I was very good. I'm telling you, I was dying on the court for 40 minutes.
"I get super dizzy. I think I have a small heat stroke for 40 minutes. Couldn't feel like fresh. I try to cool down. But even with the ice towel, the water, I think my body was super warm."
Monfils took the first set but began to struggle early in the second set, bending double between points and barely attempting to contest some games.
The Frenchman told umpire Blom, "I'm shaking, I'm dizzy," and warned he was in danger of collapsing.
Djokovic was also struggling in the incredible heat but raced through the third set and, although Monfils found more fight in the fourth, the Serb wrapped it up in two hours and 45 minutes.
The Australian Open has an Extreme Heat rule which requires an index combining temperature and humidity to reach a certain level before play is stopped.
But Djokovic believes tennis chiefs are in danger of putting business before players' health.
The six-time Aussie Open champion said: "They were really tough conditions, brutal, especially the first hour and a half.
"I think, you know, there are certain days where you just have to, as a tournament supervisor, recognize that you might need to give players few extra hours until it comes down.
"I understand there is a factor of tickets. If you don't play matches, people will be unhappy.
"People might say, 'Well, at this level you have to be as a professional tennis player, fit. It's the beginning of the season.
"You kind of work and train hard to be able to sustain these kind of conditions, to be tough.
"But I think there is a limit, and that is a level of I guess tolerance between being fit and being, I think, in danger in terms of health.
"Today was right at the limit."
Djokovic admitted his troublesome right elbow, which forced him to take six months off, was still not right.
The former world No 1 said: "The elbow is still not 100 per cent, but building.
"I have a lot of faith and self belief. I know what I'm capable of.
"Coming on this court, the most successful of my career, is always a special feeling."
The Australian Open has an extreme heat rule, but it is enforced only if humidity is high as well as the temperature.
Nick Kyrgios, the big home hope for the singles, strangely opted to keep up his commitment to play doubles with pal Matt Reid despite the ridiculous conditions.
Monfil advised his fellow players to retire if conditions got too much. He said: "Good luck to them.
"I think sometime, yeah, we put our body at risk. Just be smart. If you have to give up, you know, it's not a shame ."
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