This year's Australian Open has been dubbed the Australian Oven as the heat caused players and a ball boy to collapse. Organisers said temperatures peaked at 42.2 degrees Celsius in the early evening on Tuesday.
The scorching heat at Melbourne Park prompted players to cool off between points with bags of ice on their heads or draped over their necks. Little relief was expected this week, with similar heat forecast until Friday
Canadian qualifier Frank Dancevic criticised tournament organisers for forcing players to compete in "inhumane" condition. He fainted during the second set of his first round match against France's Benoit Paire and passed out for a minute.
A ball boy required medical attention after collapsing during Milos Raonic's 7-6(2) 6-1 4-6 6-2 victory over Daniel Gimeno-Traver.
Caroline Wozniacki said it was hot enough to melt her water bottle: ''I put the bottle down on the court and it started melting a little bit underneath. It felt like I was playing in a sauna.''
The tournament's "extreme heat" contingency plan was put into force for women's matches on Tuesday, allowing an extra 10-minute break between the second and third sets, but officials said the majority of matches were completed without calls for medical attention.