Grigor Dimitrov stood one win away from the biggest title of his career on Saturday after ending his Jack Sock jinx to reach the final of the season-ending ATP Finals at the 02 Arena.
The Bulgarian, finally beginning to look the real deal after year's weighed down by comparisons to Swiss great Roger Federer, produced more dazzling tennis to win 4-6, 6-0, 6-3 and set up a Sunday showdown with fellow debutant David Goffin.
With Federer stunned earlier by Goffin, who Dimitrov thrashed in group play earlier in the week, the door had opened tantalisingly for the 26-year-old to go on and collect the biggest title of his career to date.
But Sock had won their last two meetings having saved match points, most recently at Indian Wells this year, and those demons were lurking for Dimitrov as victory loomed.
Poised for victory at 5-3 40-15 in the decider he made two nervy errors then ballooned a forehand out on a third match point. As proof of his greater mental fortitude these days, however, Dimitrov got the job done at the fourth attempt.
Victory means he will move above Alexander Zverev and end the year as world number three, with only all-time greats Federer and Rafael Nadal ahead of him.
"I don't know what to say. This took a lot out of me," Dimitrov, the first debutant to reach the semi-finals after going unbeaten in round robin play since Andy Murray in 2008, said on court. "But my belief was good today."
Asked how he had controlled his nerves when serving for the match, Dimitrov said: "You have to. I was very composed and didn't let negative thoughts come to my head.
"If I'd have been broken in the last game then tough luck, I would have gone down the other side and played again. I'm just so humbled to be able to play the final tomorrow."
Sock had gate-crashed the London showpiece by winning the Paris Masters and catapulting up the standings and became the first American to reach the semi-finals since Andy Roddick in 2007 when Shanghai was the host city.
While his journey came to a halt, the 25-year-old said he now feels like he belongs at the top of the game.
"Shouldn't have been here in the first place," he said. "I mean, to be here, my first appearance, to make the semis, getting through a pretty tough group, that's a big confidence booster for me.
"Now I want to go and play some golf."