Extreme heat stops play at the Australian Open

Extreme heat is once again threatening to cause havoc at the Australian Open after players were hauled off courts during the opening round of qualifiers in Melbourne.

With temperatures reaching 42 degrees Celcius (108 degrees Fahrenheit), play was stopped for around two hours as officials enforced the Extreme Heat Policy -- which allows them to bring players off court if the mercury tips over 40 degrees Celcius (104 degrees Fahrenheit).

According to the New York Times' tennis correspondent Ben Rothenburg, players were even told it was too hot to practise.

Before this year's opening Grand Slam of the season, Australian National University's Liz Hanna called on organisers to change their policy and even postpone full days of play if necessary.

"Their [tennis players] bodies are the instruments of their trade," she told ABC. "When we do get those days around 40, it really is inappropriate to expect them to play.

"If we want to be really fair and actually test performance and not simply heat endurance, those days should be postponed."

The Extreme Heat Policy at the Australian Open hit the headlines in 2014 when many players complained about being forced to play in searing temperatures.

Frank Dancevic was one player affected, when he fainted during a match with Benoit Paire."I couldn't keep my balance any more and I leaned over the fence, and when I woke up people were all around me," Dancevic said after his match. "It's hazardous to be out there. It's dangerous. Until somebody dies, they're just going to keep playing matches in this heat."

The Australian Open isn't the only tournament affected by extreme heat. At Wimbledon last year a ball boy collapsed as temperatures reached the highest ever recorded at the south-west London slam, while there was a record number of withdrawals at the U.S. Open in September, much to Roger Federer's dismay.