Djokovic won his second round match against Gael Monfils 4-6 6-3 6-1 6-3 in two hours and 45 minutes as the temperature hit 39C.
Monfils took the first set but suffered in the second, complaining of dizziness and leaving the court with a doctor, said BBC.
"For sure we took a risk," the 31-year-old Frenchman said.
"We both have the same conditions but I think it's maybe a little bit too hot."
The extreme heat policy at the Australian Open does not use a simple maximum heat, rather a combination of factors including temperature, humidity and wind speed.
