Novak Djokovic won an epic match against Stanislas Wawrinka for the second time this year to reach a fourth consecutive US Open final.
The pair played arguably the best match of the season at the Australian Open, which Djokovic eventually won 12-10 in the fifth set, and the latest edition was only slightly less dramatic.
Wawrinka twice led as he looked to follow up his win over defending champion Andy Murray with an even bigger scalp, but Djokovic is a master of coming through such matches and so it proved again.
The world number one was never at his best but he had more left in the tank in the fifth set and ground out a 2-6 7-6 (7/4) 3-6 6-3 6-4 victory after four hours and nine minutes.
Djokovic said: "These matches are what we live for, what we practise for.
"It was obvious that Stan played more aggressive, he played better tennis. I was trying to hang in there, trying to adjust. I had to run a lot, I wasn't playing as well as I wanted but all the credit to him for playing so well.
"I was so fortunate to play my best tennis when I needed to."
The first set was an absolute horror show from Djokovic, who dropped his serve three times in a row, throwing in four double faults.
Wawrinka, the man playing in his first grand slam semi-final, was far more composed than the one through to his 14th semi-final in a row.
"I was so fortunate to play my best tennis when I needed to" - Novak Djokovic
Djokovic improved at the start of the second set but Wawrinka withstood the pressure in the fourth game, saving three break points, and then took his third chance to break in the next game when the Serb sent a forehand long.
Wawrinka was playing with the same authority he had against Murray, matching Djokovic in even the most brutal rallies and hitting both his one-handed backhand and forehand with tremendous zip.
Djokovic's mood was not improved when he received a warning from umpire Enric Molina for coaching, but he levelled at 4-4 when Wawrinka shanked a forehand.
The tie-break was high quality but Djokovic always had the edge, bringing up three set points and clinching it on the second with a cross-court forehand winner.
The world number one was certainly the favourite to go on and win and it was Wawrinka's turn to fall foul of Molina after he whacked a ball angrily into the crowd.
The cause of his frustration was a Djokovic break point in the opening game of the third set, but the Swiss saved it with an excellent serve.
Both men then proceeded to hold serve comfortably as the intensity of the match lulled, until Djokovic inexplicably played a terrible game to be broken to love and lose the set.
This was a new position for Wawrinka, who has not beaten Djokovic since 2006.
But Wawrinka was under pressure straight away at the start of the fourth set and a double fault handed his opponent a 2-0 lead.
In the next game he earned a point penalty for smashing his racket, bouncing it hard on the ground and then snapping it over his knee just to be sure.
Soon after, Wawrinka left the court for a medical timeout after appearing to complain to the trainer of a problem with his left thigh or groin.
Djokovic held on to his advantage to level the match once more and Wawrinka was beginning to look understandably tired.
But the Swiss held on to his serve to lead 2-1 in the decider after a quite remarkable game that lasted 21 minutes.
There were 12 deuces, five break points and some stunning shots, none better than the backhand down the line Wawrinka produced to save the fourth break point.
Both players whipped the crowd into a frenzy before Wawrinka eventually sealed it, but any thoughts that it could be a crucial moment were quickly dispelled as Djokovic held comfortably and then finally broke serve to lead 3-2.
There was no back for Wawrinka, and Djokovic clinched the victory with an ace.