Dustin Johnson will face rising star Jon Rahm in the WGC-Dell Technologies Match Play final after the world number one recovered from a wobble to beat Hideto Tanihara one up.
Johnson looked set to be cruising in his semi-final against the Match Play debutant when he was three up through seven holes at Austin Country Club, but the surprise package from Japan mounted a stirring fightback.
Four birdies in seven holes resulted in the world number 60 moving back to all square after 14 and Johnson might have wondered if it was not his day when he spurned chances to move back in front.
The U.S. Open champion, eyeing a third consecutive tournament win, had not been required to play the par-three 17th all week, but the top seed took the upper hand with a birdie at the penultimate hole after a magnificent tee shot.
Tanihara could only make par, but had a great chance to take a gripping contest to a play-off when Johnson's approach shot found the rough, with the 54th seed on the green.
But Tanihara was unable to sink his birdie putt to prolong the match, enabling Johnson to recover by salvaging par and setting up an eagerly-anticipated showdown with Rahm.
Spaniard Rahm had long since sealed his place in the final after ending Bill Haas' challenge with a three and two victory.
The impressive Rahm has gone from strength to strength this week and continued his upward momentum despite falling behind for the first time since Wednesday when Haas rolled in an expertly judged birdie putt from the edge of the green at the third.
Rahm, seeded 21, hit back to lead following back-to-back gains at five and six before surging away from the American by winning the 13th, 15th and 16th holes courtesy of further birdies from the former amateur world number one.