Novak Djokovic says Australian Open organisers are risking players' safety by asking them to play in sweltering conditions.
The Serb was on court during the hottest part of the day on Thursday as he overcame Gael Monfils 4-6 6-3 6-1 6-3 in their second-round match, the thermometer touching 40C in the shade during the encounter.
Monfils says he felt like he was "dying on court" during the contest, while Djokovic admitted that conditions were right on the limit of what is acceptable.
The Australian Open does have an extreme heat policy but that does not come in to consideration unless temperatures pass 40C, while other factors like humidity and wind speed are also taken in to consideration before play is suspended.
Djokovic has suggested organisers are asking too much to expect the players to compete in such conditions and has asked them to consider the players' health before sending them out on court.
He said: "You 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 tolerance between being fit and being in danger in terms of health. It was right at the limit.
"Our sport has become an industry, like most of the other global sports. It's more business than a sport. At times, I don't like that. What is most important for us is our health and what happens after our career, after you're 30, 35. There are many players that are struggling."