Federer and Cilic caught in frenzy over controversial Australian Open roof decision.

Did closing the Rod Laver Arena roof help Roger Federer win his 20th grand slam title?

Federer doesn’t think so, but even he admits he was surprised that Australian Open officials opted for an indoor final on Sunday night.

Creating a storm of controversy, tournament directors opted to close the retractable roof at Melbourne Park with the temperature above 37 degrees as the match began at 7.30pm.

Federer prevailed 6-2 6-7 (5-7) 6-3 3-6 6-1 over Marin Cilic in an air-conditioned Rod Laver Arena.

Cilic said he practised in the Melbourne heat to prepare for the match, calling it "very, very difficult" to adjust when organisers made the late call.

"Throughout the tournament I played all my matches outdoors, also preparing (for) a hot day," Cilic said.

"To play with the roof closed, it's difficult. That decision, could it have been different? I guess so.

"They didn't ask me.

"It was way, way cooler than I expected. That was very, very difficult."

The decision was slammed by Australian great Pat Cash, who tweeted "Roof closed????? Isn't this an outdoor tournament? Fed must of (sic) been rubbing his hands..."

Roof closed????? #ausopen isn’t this an outdoor tournament? Fed must of been rubbing his hands together when he heard the news. #cilic needed some heat ,wind to upset Fed!

A post shared by Pat Cash (@therealpatcash) on Jan 28, 2018 at 1:01am PST

Former world No.4 Greg Rusedski also railed against the "absolutely ridiculous" decision, while Australian Open doubles winner Jamie Murray said he "couldn't believe" it.

A roof closure was predicted to favour Federer, seven years Cilic's senior.

Former US tennis star Jim Courier said the muggy conditions would slow the ball down, likely favouring Federer.

“It can be very muggy in there and make things very heavy, slow the ball down, and if it slows things down at all, it probably helps Roger more than it does Marin,” Courier said.

LISTEN: Jessie Stephens thinks the fact young tennis players behave like brats is on us. Post continues after audio.

The Swiss champion has a ferocious indoor record, though Cilic is no slouch in air conditioning with eight of his 17 titles won indoors.

"I wasn't sure if it was good for me or not, to play under the roof or not," Federer said.

"Of course, I backed myself in sort of indoor conditions. This is where my first success ever came.

"I do think back that usually when I play indoors, it's good for me. But I didn't mind the heat, to be honest.

"I thought maybe for a bigger guy like Marin, maybe it's also going to slow him down faster throughout the match.

"At the end, it's not my decision. I was surprised to hear they had the heat rule in place for a night match. I never heard that before.

"Half an hour before, we got the word that it's going to be indoors. For me, it doesn't change anything in the preparation, to be honest.

"I was ready for either."

The decision ran counter to the tournament's previous practice.

While ultimately a decision for tournament referee Wayne McEwen, the stated policy required both the ambient temperature to be above 40 degrees and a wet bulb globe temperature (WBGT) above 32.5 degrees.

The ambient temperature peaked at 37.7 degrees one hour out from the start of the final.

Bureau of Meteorology figures said the WBGT shade temperature was just 26.9 at 8pm, well short of the threshold for closing the roof.

Statement on roof closure. pic.twitter.com/BBwNx6b8Lc

— #AusOpen (@AustralianOpen) January 28, 2018

A statement from tournament organisers said the a reading of 32.7 degrees was registered at 6:30pm - though it's understood that reading was taken in the sun, with the final to be staged under shade.

"With no dramatic reduction in the WBGT reading forecast (8.30pm forecast was 32.5) the referee exercised his discretion and called for the roof to be closed," the Tennis Australia statement read.

Novak Djokovic and Gael Monfils complained after struggling through oppressive 39-degree heat in their second-round match, while other players and commentators called for more protection. But the roof was never closed.

Meanwhile, women's finalist Simona Halep, who lost in a gruelling three-set match against Caroline Wozniacki on Saturday night, was hospitalised for dehydration following the tournament, ESPN reports.

She is reported to have been treated for about four hours during Saturday night, before being discharged on Sunday morning.

Simona Halep in hospital days after #AusOpen final https://t.co/o5M3IGcw1h pic.twitter.com/i0VQ2T18R9

— Sun Sport (@SunSport) January 28, 2018

Open organisers have pledged to review the policy before the 2019 tournament.

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