MELBOURNE: Iron-clad defence triumphed over all-out attack as Andy Murray overhauled Milos Raonic 4-6 7-5 6-7(4) 6-4 6-2 on Friday to book another Australian Open final against Melbourne Park nemesis Novak Djokovic.

World number two Murray came from behind twice to topple the rangy Canadian, who was troubled by a leg injury and finally capitulated after playing majestically for most of the four-hour and three-minute contest at a flood-lit Rod Laver Arena.

After levelling the match at two sets-all, Murray broke Raonic in the opening game of the decider and the flustered 13th seed smashed his racquet in frustration before promptly crumbling.

Four-times runner-up Murray roared to a 4-0 lead before closing out the match with a dismissive crosscourt winner to reach his fifth final at Melbourne Park and fourth against the Serbian world number one.

"I started to get a slightly better read on his serve later on and that was the key," Murray, beaten by Djokovic in last year's final, said in a courtside interview.

"He definitely slowed down in the fifth set for sure which was unfortunate for him," the Scot added of Raonic's injury.

"I obviously got a bit lucky on that but you just try to focus on your side of the court."

Murray's trips to the final have all ended in heartbreak, but he will have taken heart from his fighting comeback and ability to defuse Raonic's overwhelming power game.

A match pitting one of the game's finest servers against a returning maestro promised fireworks but few would have tipped Raonic to break his opponent to love in the opening game.

The 25-year-old saved three break-points in the next game then held the advantage to close out the set with a huge serve down the 'T'.

Having missed break point chances at 1-0 and 3-2 in the second set, Murray had to bide his time but he kicked the door open with a brilliant crosscourt passing shot to set up a set point at 6-5.

The Canadian chanced a serve-volley but netted Murray's sharp return and the Scot pumped his fist in delight.

The tension kept rising as the third set went into a tiebreak, and Raonic pounced on a weak second serve from Murray to take a 3-1 lead.

Serving masterfully, Raonic nervelessly rocketed a smash that clipped the line to reach 5-2 before closing out the marathon 58-minute set with an ace.

UPSET THREAT

Though the Rod Laver Arena rumbled with the threat of an upset, Raonic barely celebrated and marched straight off court.

He exited again after holding serve to lead 2-1 for a medical time-out on a leg injury but he jogged back out onto court and appeared untroubled.

That was until the seventh game, when he was broken to love in an error-strewn game as Murray ramped up his returning game.

Raonic grimaced as he had his right leg worked on by a trainer after holding serve to trail 5-4. But he shrugged off the injury to raise two chances to break back.

Murray saved them both and blasted a serve down the 'T' to level the match.

Having appeared a model of composure, Raonic finally showed the strain and smashed his racquet into the blue hard-court after being swiftly broken in the opening game of the decider.

From there the sting went out of the contest as Murray's laser-sharp focus allowed him to roar to a 4-0 lead.

The Scot struck an exquisite backhand volley to bring up three match points and after hammering the winning crosscourt forehand, savoured one of his finest wins at Melbourne Park.