Maria Sharapova and David Nalbandian lambasted the Australian Open's extreme heat policy on Tuesday after they struggled with the stifling conditions during their first-round matches.

With the mercury standing just short of 40 degrees celsius, all unstarted matches were suspended on the outside courts for several hours. But under the rules, players already on court have to play on and finish their matches.

"It's inhuman to play three hours in that kind of heat," Sharapova said following her 6-3, 4-6, 9-7 win over France's Camille Pin.

"I don't think our bodies were made to do that. When it's that hot your mind doesn't work properly," added the Russian, who looked dazed during the closing stages of the match.

Sharapova took a medical time out during the contest, which included a 10-minute heat break after the second set.

Play was restricted to the two main courts -- Rod Laver Arena and Vodafone Arena -- where action was only possible because of the retractable roofs. These can only be closed between matches. Temperatures later exceeded 50 degrees.

Belgium's Christophe Rochus became the first casualty to the draining weather on Tuesday, withdrawing with breathing problems after 13 games of his first-round match against France's Sebastien Grosjean.

VISIBLY WILTED

Serb Janko Tipsarevic was two sets and two match points up on Argentine eighth seed Nalbandian before he visibly wilted in the heat, finally retiring when last year's semi-finalist had opened a 2-1 lead in the fifth.

"I was tired from the first point. It's not tennis any more, it's who is going to last longest in the sun," the world number 64 told reporters.

Nalbandian was extremely critical of the situation.

"The thing I didn't understand is why they didn't call the match [off] after 40-something degrees," Nalbandian said.

"I mean, why didn't they stop all of it? It's very disgusting playing like this."

France's Julien Benneteau even lost consciousness after his five-set defeat to Paul Capdeville.

"Several times I thought about quitting but I pushed myself to my limits, vomiting at the end of the fifth set. I was scared," he said.

"Later when I went into the dressing room, the tournament doctor used a drip to try to hydrate me. During this procedure, I was tired, I fell asleep but the doctor shook me and said 'Stay with us'. He was quite scared."

Organisers kickstart their extreme heat plans when the thermometers pass 35 degrees and when the Wet Bulb Globe Temperature, a combination of ambient air temperature and humidity, exceeds 28 degrees.

Players are also able to use ice vests when the heat exceeds 26 degrees.

Sharapova was among the players to take advantage of the vests -- ice-filled tubes worn round the neck and chest to fend off the punishing heat.

The roof was retracted when Spanish second seed Rafael Nadal and Robert Kendrick began their match on the showpiece court.

With play suspended for more than seven hours, officials are now facing a huge backlog of matches.