Justin Thomas admitted he was distracted by the prospect of becoming world No 1 as he suffered a 3&2 defeat to Bubba Watson at the WGC-Dell Technologies Match Play.
Victory for Thomas would have earned him enough points to dethrone Dustin Johnson at the top of the world rankings, but he was unable to reproduce his form of the first four days in Austin.
Watson took control of their semi-final from the outset as he converted a neat pitch to six feet at the first, and he followed another birdie at the fifth with a well-judged 25-foot putt for eagle at the sixth which took him three up.
Thomas pulled one back when Watson pulled his tee shot at the next and failed to get up-and-down, and the world No 2 holed from outside 20 feet for birdie at the ninth to reduce the deficit to just one at the turn.
But Watson responded with a birdie at 10 before he went three up with six to play when Thomas tugged his second shot into water at the 12th and ran up a bogey-six.
The American pair traded pars over the next three holes, and Watson closed out a convincing victory with two holes to book a clash against Kevin Kisner in the 18-hole final.
Asked if the world rankings situation had affected his focus, Thomas admitted: "I haven't had such a hard time not thinking about something so much, and that really sucked. I couldn't stop thinking about it, to be perfectly honest, but I need to be mentally stronger than that, and understand that it's just a match.
"But at the end of the day, obviously I didn't play very well, but I definitely didn't give him the match. He made a lot of birdies out there and played well enough to be deserving to be in the final match.
"I wasn't in the best mojo out there. I wasn't hitting very good shots and wasn't taking advantage of opportunities. I made some good putts to stay where I was, but I did hit a lot of good putts that just burned the edge out there."
Kisner, meanwhile, ended Noren's impressive run in the tournament in a high-quality match that went to extra holes, with neither player leading by more than one hole throughout.
The American led after Noren bogeyed the first, and the pair both reeled off four consecutive birdies from the third before Noren added further birdies at seven and eight to make it six in a row and snatch the lead at the turn.
But Kisner then drained a huge eagle putt from over 50 feet for a remarkable eagle at the 12th, although the putts then dried up for both players as they each parred the final six holes to remain all square.
They headed back to the par-five first and both came up short of the green with their second shots, but after Kisner pitched to six feet, Noren misjudged his putt for eagle from the fringe as his ball veered left and left him over 10 feet for birdie.
The Swede's second putt grazed the left edge of the cup, and Kisner held his nerve to rattle in the winning birdie which ensured an all American final.