He all but sealed the win with a 44-foot birdie putt across the green at the last and although many of his nearest challengers still had several holes to play they faced a tough task to catch the leader and so it would prove.
But while he was just two shots outside the top-10 starting yesterday's final round, he got off to a horrific start and carded a six-over-par 78 to finish 54th on two-over.
"Amazing; to be at Arnie's place, it's a tournament that I used to watch on TV when I was back home in Italy and it's a magical place", Molinari, who had to wait nearly two hours before his victory was confirmed, said. "And yeah, just started making putts, one of my best putting rounds ever".
"It's great, to do it here, to get it done here at this place knowing that my wife and the kids were watching back home, it's just a special, special one", Molinari said of his victory.
"You know, it was the first week as a Callaway player, so happy to see that the switch I made wasn't that insane as some people thought", said the Italian. "I'm looking forward to seeing what happens going forward and playing in some bigger events". McIlroy finished at eight under and tied for sixth, amazingly his worst finish of 2019.
"I probably played too safe".
"No game plan really, just trying to hit good shots and give myself chances", Molinari said.
He got on the par-5 16th in two before two putts helped him take the outright lead at 11 under and he sealed his stunning round with that monster birdie putt at the last. But after a 25-foot birdie putt on the third hole to briefly tie for the lead, McIlroy played the next 12 holes with two bogeys and 10 pars.
"THE PLAYERS next week is one of those weeks that you circle in the calendar at the beginning of the year", Molinari said.
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Witnesses said almost a dozen students had been pulled from the ruins, but it was not yet clear if any were dead. Associated Press video from the scene showed a few dust-covered children carried from the rubble, to cheers.
Molinari has four victories worldwide in his last 17 starts over the last nine months, and the Italian pointed to the first of those victories for sparking his turnaround.
Defending champion Rory McIlroy, who had moved into contention, could only manage an even-par 72 to end up tied for sixth at eight under.
Harding got down in two from the front of the green on the par five 18th and then had to wait and see if anybody could catch him.
It's safe to say that Molinari did just that on Sunday, and he did Mr. Palmer proud. "I think obviously confidence has to do a lot with it".
The final day began with a clear indication that Tiger is ready to return at the Players Championship this week despite his neck injury. When I won previous year, playing with Rory in the last few groups, it wasn't easy at all.
Molinari closed with a 62 to blow away the field in the Quicken Loans National.
The 36-year-old is on fire after an outstanding 2018 season in which he won European Tour's Race to Dubai, became the first Italian to bag a major when he triumphed at The Open and was the driving force of Europe's victory over the United States in the Ryder Cup.
"I kind of see the Claret Jug every day when I'm at home, so I'm used to seeing it", said Molinari, drawing a laugh in the media center.