A once in a century heatwave created havoc at the Australian Open [Images] in Melbourne on Wednesday, forcing tournament organisers to cancel matches and invoke the extreme heat policy to protect the health of the players.

The tournament match referee Wayne McKewen ordered the roof on the Rod Laver centre court shut and all matches were suspended on the outside courts as the temperature soared to a stifling 43 degrees Celsius.

The players were left soaked in sweat and gasping for air in the sweltering heat while spectators abandoned the stands to watch matches on television sets in bars and shaded areas at Melbourne Park.

The brutal conditions proved too much for the swarms of bogong moths that flutter around the stadium's bright lights, with dozens dropping dead on to the main court.

The Australian Open has always been played in brutal conditions but organisers are on high alert this year after the Bureau of Meteorology forecast the worst heatwave in more than 100 years.

WILTING IN THE HEAT

The defending men's champion Novak Djokovic [Images] quit his fourth-round match against Andy Roddick [Images] on Tuesday after wilting in the heat while Victoria Azarenka almost fainted from exhaustion in her fourth-round match.

Wednesday's quarter-final between Serena Williams [Images] and Svetlana Kuznetsova [Images] was held up for almost half an hour between the first and second sets while the centre court roof was closed.

"Before they did that, I thought I was having an out of body experience," Williams said after her 5-7, 7-5, 6-1 victory.

Russia's [Images] Elena Dementieva [Images] was less fortunate, made to play her quarter-final against Carla Suarez Navarro of Spain with the roof still open.

The temperature at that stage was just approaching 40 degrees and although Dementieva won 6-2, 6-2 she said the roof should have already been shut.

"I'm really surprised, you know, 'cause when you see the forecast, it was going to be 41 today," she said.

"I think if you have a roof, why not use it? Not only for the players, but for the spectators as well."

Rod Laver himself agreed: "They say we're going to have this sort of heat for the next three days, why not just close it right now and leave it closed?" he told reporters.

"It's just wonderful that they have a roof they can close, so take advantage of it."

Organisers use a complicated formula that combines the air temperature, wind, solar radiation and humidity before deciding when to invoke the extreme heat policy.

Apart from closing the roof and suspending play on outside courts, the policy allows players to use ice vests and have extended breaks between sets.

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