MELBOURNE • The Australian Open's extreme-heat policy came under increasing scrutiny yesterday, as players struggled through a second straight day of 40 deg C heat at Melbourne Park.

France's Alize Cornet was in visible distress during her third-round match against Belgian Elise Mertens, and a ripple of concern went through the Hisense Arena crowd when she lay down on the court after serving a double-fault.

The 27-year-old had a medical assessment when she returned to her chair, before battling on to a 5-7, 4-6 loss.

"Playing in this condition is of course very dangerous for the health of the player," former world No. 11 Cornet said. "The limit of not playing the match is really high... I think this limit should be a little lower because playing in this condition is not nice for anyone."

The extreme-heat policy, which involves closing the roofs of the stadiums and suspending matches, is invoked when the ambient temperature exceeds 40 deg C and the wet bulb globe temperature index reading exceeds 32.5 deg C.

The Australian Open has only twice invoked the policy - in 2009 and 2014.

Organisers said the conditions yesterday did not meet the thresholds. But they were criticised on social media for failing to call a halt to play in a city where outdoor construction workers often down tools for health and safety reasons when temperatures push past 35 deg C.

Tournament director Craig Tiley said the year's first major was one of the only events in the world to actually have a heat policy.

"The policy is from consultation with the players, and remember in most places... they don't have a heat policy," he said. "Throughout the site we have ice misters, there's plenty of water. For the players there are ice vests, there are longer periods of rest and they of course have shade on their chairs.

"These are professional athletes. We are at the end of the day an outdoor event."

Six-time champion Novak Djokovic described Thursday's conditions as "brutal", complaining it was hard to breathe and they were "right on the limit". His opponent Gael Monfils said he felt he was "dying" during his four-set loss.

Defending champion Roger Federer escaped the worst on Thursday, playing a night match on the Rod Laver Arena, but said players have "to play in all conditions".

He admitted it was a tough call for organisers to make on whether to halt play or not.

He asked: "What do you do? You stop all matches? The lucky guys on the big courts, they get to play under the roof. The other guys get postponed till the next day? Is that great? That's not great either."

Nick Kyrgios and Jo-Wilfried Tsonga also took to centre court in cooler conditions yesterday, with Kyrgios outlasting his childhood idol 7-6 (7-5), 4-6, 7-6 (8-6), 7-6 (7-5) under the lights.

Tsonga, the 15th seed, had looked primed to take the electric third-round fight into a fifth set when he stormed to a 4-1 lead in the final tiebreak, but Kyrgios roared back to seal it when the Frenchman hammered the ball into the net on the first match point. Kyrgios will next face third seed Grigor Dimitrov for a place in the quarter-finals, the man he beat in the last four of the Brisbane International this month.

"It was amazing, I'd never won a match on this court coming here," Kyrgios, a 12-year-old fan when Tsonga lost to Djokovic in the 2008 final here, said in the post-match interview on court. "Playing Jo, obviously I was very nervous. I was just happy to get through."

REUTERS, AGENCE FRANCE-PRESSE

AUSTRALIAN OPEN

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