World Number One Dustin Johnson will take on Jon Rahm in the final of the WGC - Dell Technologies Match Play but he was pushed all the way by Hideto Tanihara at Austin Country Club.
Johnson has been in brilliant form all week, not once trailing in a match and having not yet gone beyond the 16th in his five matches before Sunday's semi-final.
At three up after seven holes, it looked like business as usual but Tanihara - making his debut in the event - has been one of the stars of the week and he took the American up the last before losing by a single hole.
Johnson now has the chance to become just the second player after Tiger Woods to win back-to-back World Golf Championships after his victory at the WGC - Mexico Championship at the start of the month.
"It was a tough match," said Johnson. "I didn't feel like I really gave him anything, just hit some great putts that didn't go in the hole there on the back nine, ten, 11, 12, 14, 15, 16. And we're all square on the 17th tee.
"But I felt like I played really well. I drove it well. I didn't really give any holes away. He played really well.
"I needed a tough match because I know the final is going to be a tough one. Me and Jon both are playing really well. It's going to be a tough match."
Tanihara can start planning for the Masters Tournament after moving into the top 50 in the Official World Golf Ranking and he can be very proud of his week's work.
Johnson rolled in a 25-footer to make it six birdies and six wins on the opener this week but a poor approach to the second resulted in a three-putt and an all square match.
Me and Jon both are playing really well. It's going to be a tough match - Dustin Johnson
A par on the next despite a drop off the tee moved Johnson two ahead and when he made a mockery of the sixth, hitting a 210-yard eight iron to 35 feet and holing the eagle putt, he was two up.
A birdie on the next seemingly put him in control but Tanihara hit back on the eighth and when Johnson failed to find the putting surface on the tenth and surrendered a bogey, the gap was down to one.
The Japanese had a chance to get all square at the 12th with an eagle putt but he needed three attempts to get down and Johnson was gifted a two up lead.
The 38 year old is a tough competitor, however, and hit back with a pair of birdies on the 13th and 14th to once again even the contest up.
Johnson was taken to the 17th for the first time and he won it with a birdie after a tee-shot to seven feet, holing from similar range on the last to win one up.