Bubba Watson will take on Kevin Kisner in the WGC - Dell Technologies Match Play final after a dramatic morning of action at Austin Country Club.
Watson was the first to advance from the semi-finals as he caused an upset by beating Justin Thomas 3 and 2, preventing his fellow American going to the top of the Official World Golf Ranking in the process.
The second semi-final was a high-quality affair with ten birdies and an eagle in the first 12 holes but after the next six were halved in pars, Kisner took down Alex Noren on the first extra hole.
A win for Watson will make him just the fifth player after Rory McIlroy, Tiger Woods, Ernie Els and Phil Mickelson to win multiple Major Championships and World Golf Championships, while Kisner is going in search of a first WGC title.
I had a good opportunity on the last but it slipped away. That's how it goes sometimes - Alex Noren
For Noren, it is a disappointing end to a brilliant week that saw him emerge from his group with a 100 per cent record before defeating Patrick Reed and Cameron Smith.
"I had so many chances, especially from nine forward," he said. "But it's tricky with the putting here, it slopes a lot. That's it.
"I felt pretty good but it was tough to read the lines right and you start to doubt the lines. I had a good opportunity on the last but it slipped away. That's how it goes sometimes."
The Swede missed the green with his approach to the first and while he played a nice chip from a tough position, he could not make par and Kisner took the early initiative.
The American holed a 30-footer for birdie on the third to heap the pressure on but Noren hit back from 11 feet to stay just one back as the duo traded blows, each making four gains in a row to the sixth in high-quality putting displays.
Kisner then missed the green on the seventh and Noren took advantage, making a fifth one-putt birdie in a row from 18 feet to square up the contest.
Noren needed two putts to make a par on the eighth but Kisner missed a short one for par after finding trouble off the tee and the nine-time European Tour winner led for the first time.
Good chances went begging for Noren on the tenth and 11th and Kisner made him pay on the next, holing a 50-foot putt for eagle to get back on level terms, with Noren mising a putt from eight feet for victory on the last and sending the match back to the 12th.
I didn't really make any mistakes - Bubba Watson
Both men were just short of the green after two shots but while Kisner chipped to close range, Noren's putt drifted to the left fringe, allowing Kisner to win with a birdie.
"It was a tough match," said Kisner. "He kept hitting it in there close and if he probably would have made any of those putts, it would have been tough to come back from. Hung in there and made putts when I needed to and was fortunate to get a win and go to the play-off."
Watson got a fortunate bounce on the first and was left with a seven-foot putt for birdie which he made to move one up.
Both men came up just short of the fifth green off the tee but Thomas was left with an awkward stance and could only make par, with Watson getting up and down to double his advantage.
The two-time Masters champion was behind a tree off the tee on the sixth but in typical fashion bent his approach to 25 feet and made an eagle to go three up.
Another poor tee-shot saw Watson miss the green on the par three seventh and when he failed to get up and down, Thomas had a first win of the day with a par.
The gap was cut to one at the turn when Thomas holed a 23-footer for birdie on the ninth but Watson made one of his own from ten feet on the next to re-establish his cushion.
Watson left a five-footer short for a win on the 11th and missed his birdie putt on the 12th but Thomas could not save par after going in the water and the gap was up to three, with the pair halving the next four.
"I didn't really make any mistakes," said Watson. "I made one mistake, I guessed wrong on number seven, made a mistake there.
"Then I made some putts early and when you make putts early, you have a chance to get the lead. I just played solid and he didn't make any putts."