Last year's runner-up Kevin Kisner went one better this year as he beat Matt Kuchar to claim the WGC Match Play title in Texas.
Kisner ended Molinari's long winning streak in match play golf in the semi-finals, before claiming 3&2 victory over fellow American Kuchar in the final at Austin Country Club.
Kisner, who was thrashed 7&6 by Bubba Watson in last year's final, struck the first blow against Kuchar with a birdie from 12 feet on the first.
That lead looked set to be short-lived when Kisner drove into a hazard on the second, but he scrambled a bogey five and Kuchar three-putted from 16 feet to let Kisner off the hook.
Kuchar got back on level terms when a par was good enough to win the fifth, but Kisner responded immediately to win the next with a birdie.
Kuchar three-putted the seventh to fall two behind, only for Kisner to make the same mistake on the ninth and see his lead cut to a single hole heading into the back nine.
An error-strewn contest continued on the 11th as Kuchar dumped his tee shot into the water on the par three to fall two down.
Both players did at least birdie the par-five 12th and also got up and down from over the green on the 13th to leave Kisner two up with five to play.
A par on the 15th was enough to move Kisner three up and he closed out the win in style with a birdie from 20 feet on the par-five 16th after Kuchar left his eagle attempt inches short.
Minutes earlier, Molinari had also completed a 4&2 win over Bjerregaard on the same hole to claim third place.
Molinari runs ends in the semis
Molinari, who hadn't been behind in any match all week before the semi-final, fought back from two down with three holes to play with birdies on the 16th and 17th, only to three-putt the 18th hole.
It was the first time the Open champion had played the 18th in competition this week after enjoying five comfortable wins to reach the last four.
The defeat also saw the Italian's long unbeaten match play run end at ten matches, after his run in Texas came on the back of him winning all five of his matches at the Ryder Cup last year.
Kisner will face fellow American Matt Kuchar in the final after Kuchar beat Denmark's Lucas Bjerregaard by one hole.
There was never more than one hole between the pair and Bjerregaard, who got the better of Tiger Woods in the quarter-finals, got back on level terms four times after Kuchar edged in front.
Bjerregaard also crucially matched Kuchar's birdie on the 17th to keep the match alive, but was unable to repeat the feat on the last and Kuchar safely two-putted for par.
Bjerregaard and Molinari will fight it out for third place in the other match on Sunday night.
Related golf content
