Brisbane QLD, Australia, 4 January 2014 | AAP

Feeling the heat in more ways than one, Lleyton Hewitt was ice cool as he fought back to clinch a 5-7 6-4 6-3 win over second seed Kei Nishikori and book a likely Brisbane International men’s final against Roger Federer.

As the on-court temperature hovered around 40 degrees, world No.60 Hewitt applied the blowtorch to the Japanese young gun in a huge shot in the arm ahead of the Australian Open.

The former world No.1 plays the winner of Federer’s semifinal with eighth-seeded Frenchman Jeremy Chardy at Pat Rafter Arena later on Saturday.

Either way, two-time Grand Slam champion Hewitt is still enjoying the best start to a summer since 2005 when he made the Australian Open final against Marat Safin.

Both Hewitt and Nishikori spent breaks between points with ice packs draped around their necks and on the back of their heads while nestled next to court-side fans as they tried to counter the sweltering conditions.

And at first world No.17 Nishikori defied the draining weather.

Hewitt, 32, was up 40-0 serving at 5-all but was still broken before Nishikori sealed the first set with a stunning backhand winner.

Rather than drop his head and succumb to the heat, Hewitt again showed his fighting spirit to break Nishikori – eight years his junior – in the 10th game and seal the second set.

On a roll, Hewitt rattled off a total of five straight games to jump to a 3-0 lead in the third and didn’t look back.

Hewitt moved to a 2-0 overall record against Nishikori, who he last defeated at Wimbledon in 2011.

Fit again after a career-threatening toe injury and back in the world top 75 for the first time in three years, Hewitt is suddenly feeling very good ahead of the year’s first Grand Slam.

“I love the battle,” Hewitt said of his fightback on Saturday.

“Mentally this is a major win to have come back and gone the distance.

“You do all the hard work in the off season so you don’t want to come here and go through the motions.

“You are retired a long time. I want to squeeze out everything I possibly can before then.”

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Peers and Murray fall in semifinals

Men’s doubles second seeds Daniel Nestor and Mariusz Fyrstenberg are the first duo through to Sunday’s final.

Nestor and Fyrstenberg saw off third seeds Jamie Murray and John Peers in straight sets 7-5 7-6(5).

After winning three titles together in 2013, Murray and Peers were hoping to add their first for the 2014 season here in Brisbane, but Nestor and Fyrstenberg had other ideas.

They will face either Roger Federer/Nicolas Mahut or Juan Sebastian Cabal/Robert Farah in the final.