Roger Federer saw off Lleyton Hewitt in four hard-fought sets to secure a US Open final against Andre Agassi.
The top seed was pushed hard but came through 6-3 7-6 (7-0) 4-6 6-3 for his ninth successive win over Hewitt.
A single break was enough to give the defending champion the first set but he had to save five set points in a desperately tight second.
Federer then dropped the third before raising his game to break in game six of the fourth and serve out the match.
With a run of eight straight wins over Hewitt going into the match, a routine win looked likely when Federer rolled through the first set and broke at the start of the second.
But the world number one has been giving his opponents chances in recent matches and did so again as Hewitt broke straight back.
The pattern was repeated in games seven and eight before Federer missed another chance to break in game nine.
Hewitt sensed his opponent was not at his most ruthless and had the chance to level with five set points in the 10th and 12th games, but he could not convert and paid the price.
Federer won the subsequent tie-break 7-0 to leave the Australian with a mountain to climb.
As ever, Hewitt looked up for the challenge, saving two break points in game four of the third before edging ahead himself in game seven and taking the set.
At last Hewitt seemed ready to take his nemesis to the brink and really test him, but he could not keep up the pressure.
Federer stayed in touch early in the fourth set, narrowly failing to break in game two, and then did so in game seven as Hewitt handed him two double faults.
After failing to build on earlier leads there was another scare for Federer at 0-30 down when serving for the match, but the top seed recovered to book his place in the final.
"It wasn't my best serving but you cannot expect to hit aces and service winners all the time," said Federer afterwards.
"Today I definitely had to survive more tough moments than in the past against him.
"I wish I could have played more consistent throughout the match but today it was tough."
Hewitt said: "I felt like I could go toe to toe with him. At least I had a little tussle with him.
"He's definitely been the standout player. He's lost three matches all year and on two of them he's had match point."