Argentine Grillo (68) curled in the winning putt at the 186-yard 16th, the same hole where he had taken the solo lead of the Charles Schwab Challenge, before needing a play-off. Grillo and American Adam Schenk, who both finished at eight-under, had two-putt pars from 26 feet at No.18 to start the play-off.

It was the second PGA Tour win for Grillo, the 30-year-old whose only other win was at the Frys.com Open in Napa in October 2015. He had four other top-10 finishes this season.

“It feels great. The wait was definitely worth it. It was long, but it was worth it,” Grillo said. “Happy to be champion in Colonial. I get to put my name right next to Roberto De Vicenzo, which is 40, 50 years ago. I'm excited.

“I said it a few times that I wasn't going to retire without winning here, and I'm lucky that I got it done in the last year before the renovations. I'm excited. I'm happy. That's the way I can put it.”

Schenk, the 31-year-old in his 171st PGA Tour event, got his second runner-up finish of the season and still seeks his first victory after a 72 playing in Sunday's final group.

RIGHT: Aaron Baddeley was the best of the Aussies in a tie for 21st at Colonial. PHOTO: Aric Becker/Icon Sportswire via Getty Images.

At No.16 in regulation, Grillo took the solo lead with a 20-foot birdie. His lead was two shots going to the 18th before a wayward tee shot to the right. His ball went into a small concrete drainage canal, then floated 150 yards or so back toward the tee box before coming to rest against a rock in the middle of the water flow.

“Well, I've done it before. I've hit it there. I knew, as soon as I saw the ball going right, I was like this is going to be a very long hole. I've been through that pain of watching the ball just roll 120 yards back,” Grillo said of the last hole.

“I knew that, if I stayed ahead of Scottie, still with a chance. If I can beat Scottie by one shot, I could still have a chance. I did my absolute hardest to make a 5 in there, and just I didn't have my driver today.”

After taking a penalty stroke with a drop, he then two-putted from nearly 20 feet for double bogey.

RELATED: Inside Grillo's winning bag

While all that was playing out at No.18, and Grillo waited to see what was going to happen to his ball, Schenk made a birdie at the 16th, his only of the round, before pars on 17 and 18.

PGA Tour rookie Harry Hall, in the final group with Schenk, bogeyed the final hole after his drive into the water to miss getting in the play-off.

“I said it a few times that I wasn't going to retire without winning here, and I'm lucky that I got it done in the last year before the renovations. I'm excited. I'm happy. That's the way I can put it.” – Emiliano Grillo.

Hall, a 25-year-old Englishman, was the solo leader after the first and second round.

He finished tied for third at seven-under with local favourite and last year's runner-up Scottie Scheffler, the World No.1 who had a hole-in-one at the 189-yard 8th hole during his closing 67.

It was Scheffler's second career Tour ace. The first came in his PGA Tour debut as a 17-year-old at the 2014 Byron Nelson in his hometown of Dallas.

Aaron Baddeley (67) was the best-placed Australian at one-under and tied for 21st, while Min Woo Lee finished joint-40th after his one-over 73, with compatriots Cam Davis, Lucas Herbert and Harrison Endycott all missing the halfway cut.