Roger Federer is through to his sixth Australian Open final after beating Stan Wawrinka in a five-set thriller.
The 17-time Grand Slam champion was at his dangerous best in the opening stages, before an injury to Wawrinka threatened to end his involvement.
After losing the first two sets, Wawrinka went off court with the trainer in tears and it looked as if the contest could end early.
But the world No. 4 soldiered on with his problematic knee taped up before attempting to stage an unlikely comeback.
He began hitting at an incredible level and the four-time Australian Open champion struggled to find the answers as Wawrinka levelled the match to 2-2.
But Federer eventually found a way through, maintaining his excellent head-to-head record over his close friend with a 7-5 6-3 1-6 4-6 6-3 victory.
Wawrinka had never beaten Federer on a hard court, or, in fact, any other surface than clay, with the 35-year-old winning their previous 13 encounters on the surface.
The 31-year-old’s record in their head-to-head doesn’t improve much in general, with his compatriot coming out on top in 18 of their 21 matches heading into this one.
And Federer extended his record to 19-3 over Wawrinka to set up his 100th Australian Open match.
Both players created break point chances in a high-quality first set but the server largely stood firm.
That was until the final service game of the set, where Wawrinka netted a forehand and allowed Federer to take the first 7-5.
The 35-year-old looked the much sharper player in the second set and got his reward to break before consolidating it to move 5-2 up.
Federer never looked like failing to see it through from that stage onwards and served it out to love for 6-3 before Wawrinka called the trainer to receive medical attention.
If Federer thought that was Wawrinka done, he was sorely mistaken as the fourth seed broke for a 3-1 lead in the third.
Another break followed as Wawrinka begin hitting at full pelt and he took the third set in just 26 minutes.
Wawrinka broke Federer for a third time in a row at the start of the fourth but the former world No. 1 responded well to break back immediately and level it up to 1-1.
Incredibly, Wawrinka found himself serving for the set at 5-4 after another break and he levelled the match to 2-2.
However, Federer regained his compusure to take the fifth set to set up a clash with either Rafael Nadal or Grigor Dimitrov, who meet on Friday.