World number one Novak Djokovic fought off Stan Wawrinka over five tense sets to master the defending champion and reach his fifth Australian Open final on Friday, where he will meet Andy Murray.
The Serb top seed won 7-6 (7/1), 3-6, 6-4, 4-6, 6-0 in 3hr 30mins and will face the British sixth seed for a third time in Sunday's Grand Slam decider.
It was Djokovic's toughest match of the tournament and his serve was broken five times in another titanic duel with the Swiss world number four.
The clash was their fourth straight Grand Slam encounter to go to five sets with Djokovic winning three of them. He lost to Wawrinka in the quarter-finals at last year's Australian Open.
"I did not play on the level that I intended," he said. "There were parts of the match where I stepped in and played a game I needed to play, but other parts where I played too defensive and allowed him to dictate the play from the baseline.
"He has great depth in his shots. Once he has control of the rallies it's very difficult to play against him.
"So it was very emotional, very tense, as it always is against a top player in semi-finals of a Grand Slam."
The top seed won through to his fifth Australian Open final, having won his previous four deciders in Melbourne. He beat Murray in the 2011 and 2013 finals.
But Murray also has form against Djokovic, beating him in the 2012 US Open and 2013 Wimbledon finals, setting up an unpredictable Melbourne Park decider.
It was not a convincing performance from the Serb, who made 49 unforced errors to 27 winners and won just 70 percent of his first serves, but crucially he broke Wawrinka's strong serve seven times.
"I think it was more mental because once you back up and start playing defensively you spend a lot of energy," Djokovic said of his mid-match lapses.
"He was the one that was dictating the rallies. There's no question about it.
"Some points of the match I did struggle physically to recover for the next one because I run a lot and he was getting a lot of balls back in play.
"I didn't have many free points on the first serve as I did throughout the tournament, so that was a significant change."
- Just not there -
Wawrinka said he too struggled mentally and was not at his best.
"I was telling my box it was tough for me to stay with him, to find a way to win points," he said.
"Because I was just trying to fight and to make some good choice, but today I was just not there."
Djokovic had lost only one of his 74 service games prior to the semi-final, but Wawrinka broke him in the seventh game of the match with a series of withering backhands.
But the Serb hit straight back with outstanding side-to-side movement to level up with the set going to a tiebreaker.
Djokovic was too strong in the tiebreak with Wawrinka too loose with his shots to drop the opening set.
The Swiss fought off break points in his opening serving game of the second set, but Djokovic double-faulted on break point in the sixth to lose the set.
Both players traded service breaks in the third set, but the world number one seized control after Wawrinka could not close out a 40-15 lead and he reeled off the next four points to take the lead in the match.
But again Wawrinka hit back with two breaks in the fourth set to take it into a fifth, just like their three previous Grand Slam encounters.
Two double-faults and an overhit backhand cost Wawrinka an early service break in the final set and another errant backhand lost him a second service to hand the Serb a winning 4-0 break.