By Ian Ransom
MELBOURNE, Jan 28 (Reuters) - The Australian Open men's singles final between champion Roger Federer and sixth seed Marin Cilic got underway on Sunday with the roof closed at Rod Laver Arena on a scorching day, triggering a hailstorm of criticism from former players.
The roofs of the main showcourts at Melbourne Park are usually kept open unless the tournament's extreme heat policy is invoked, when the temperature exceeds 40 degrees Celsius (104 F) and a key humidity threshold has been surpassed.
The temperature was 37 degrees Celsius (98.6 F) when Cilic and Federer took the court.
Former Wimbledon champion Pat Cash said the decision to close the roof would play straight into defending champion Federer's hands.
"It's an outdoor tournament -- it's like Wimbledon. Why is the roof closed?" the Australian said during commentary for BBC radio.
"The way Roger plays, he swings so hard at the ball and takes it so early, any wind or variation of the ball moving will take it away from him. It's why he's one of the best players ever indoors."
Other former players expressed disdain for the decision.
"I can't believe they've closed the roof," British doubles player Jamie Murray, the brother of three-times grand slam champion Andy Murray, tweeted.
"Absolutely ridiculous that the roof is closed for the Australian Open. GS are outdoor events. Yes it's hot but the court is under shade and an evening match," tweeted British former U.S. Open finalist Greg Rusedski.
During the first week of the grand slam, players battled through two days of 40 degrees Celsius heat fully exposed to the conditions, as organisers declined to invoke the heat policy. (Editing by Amlan Chakraborty)