Play started in sweltering conditions on the fourth day of the Australian Open, with the weather forecast predicting the temperature will reach 44 Celsius (111 Fahrenheit).

When Maria Sharapova began play against Karin Knapp just after 11 a.m. Thursday, it was 39 Celsius (102 Fahrenheit) at Melbourne Park. An hour later, it had gone up to 41 C (106 F).

Australian Open organizers invoked part of the special conditions before play began, allowing women's matches to have an extended break after the second set and players to wear ice vests during changeovers. Temperatures hit 42 C (108) at Melbourne Park on days two and three.

But it was possible that play could be suspended on outside courts later Thursday under the tournament's Extreme Heat Policy.