Making a return to elite tennis after six months out following knee surgery, Federer finally put Wawrinka to the sword 7-5 6-3 1-6 4-6 6-3 on Rod Laver Arena, becoming the oldest man to make a grand slam final since 39-year-old Ken Rosewall in 1974.

Chasing his elusive 18th major title, the 35-year-old will face either Nadal or Bulgarian 15th seed Grigor Dimitrov in the final, with that pair to square off on Friday night.

Federer has never lost to Dimitrov while he has a losing record against Nadal.

“You would probably think I have a slight better chance to beat Dimitrov than Nadal,” Federer said.

“I’m in the finals, I know that. I know I will have a chance to win on Sunday and that’s a great position to be in.

“Regardless of who it’s going to be against, I think it’s going to be special either way. One is going to go for his first slam or it’s the epic battle with Rafa.”

The prospect of a Federer-Nadal Australian Open final is a dream match-up for most tennis fans, but the Spaniard’s uncle and coach Toni sees it a little differently.

People say it’s a dream final, but when I dream, I dream about Rafael meeting the worst player in the tournament

“When we’re in a final, normally I’d prefer to be against a bad player,” Uncle Toni quipped.

“I like to watch Federer playing but I don’t want too much to be playing against him in the final.

“People say it’s a dream final, but I say that it might be for them but when I dream, I dream about Rafael meeting the worst player in the tournament.”

The pair last met in the final of a grand slam at Roland Garros in 2011 when Nadal prevailed in four sets.

The Swiss master and the Spanish bull have shared some enthralling battles over the course of their glittering careers and, all jokes aside, Uncle Toni agrees another chapter in their rivalry would be something to behold.

“The possibility of playing Federer in a final could be good for tennis and it could be good for us too,” he said.

“I have very good memories of the matches that we’ve had against Roger. But I know that when you arrive in a final against Federer it is very difficult.”

The Swiss veteran looked like he would wrap up last night’s match in straight sets and march into his 28th grand slam final – including six in Melbourne – when he was up by two sets and with Wawrinka walking off the court almost in tears to have his knee strapped.

Wawrinka’s frustration showed after going down a break midway through the second set when the fourth seed snapped his racquet over his knee, earning a code violation.

But Wawrinka, who won the 2014 title at Melbourne Park, returned for the third set from the injury time-out a driven man.

The US Open champion won 20 of a possible 26 points to crush Federer 6-1 and take the early break in the fourth.

Federer levelled but Wawrinka wouldn’t be denied when he had another three break points at 4-4 before he served out the set.

Federer left the court before the start of the fifth set for his own injury time-out after suffering tightness in his leg, although he later admitted he used it to clear his head.

With a break point hanging over Wawrinka’s head, a double fault gifted Federer a crucial fifth set break and he then served out the match to love.

“Always against Stan, it was always never going to be easy,” Federer said.

“Especially how the third and fourth set went by, I needed to react really, because he had the upper hand from the baseline.

“I thought it was going to be tough in the fifth and I think he gave me a cheap break in the fifth.

“After that, I never looked back and I could not be happier right now.”

Federer last lifted a grand slam trophy at Wimbledon in 2012 while he hasn’t won at Melbourne Park since 2010.

His victory continued an extraordinary retro vibe at the tournament, with the Williams sisters, Serena and Venus, also back in the title decider at Melbourne Park for the first time since 2003.

-AAP