A birdie on the 15th saw him move clear of the pack, which at one point included nine players tied for the lead, but he was made to wait for his win to be confirmed as Rafael Cabrera Bello continued his final round.
He won this event back in 2014, but that's his only PGA Tour victory since 2011, and he hasn't finished better than 47th so far in 2017.
"I've been pretty consistent with my tee shots, putting the ball in the fairway and getting the ball on the green, capitalising on some putts and if not just tap in for par", said the PGA Tour rookie. "I need to just keep doing the same thing I'm doing: attack the holes that suit my eye and make as many birdies as I can". I hit a lot of really good shots today and had a chance to shoot something really low.
Brandt Jobe won the Principal Charity Classic on Sunday by one shot, finishing at 14-under 202 for his first victory in 19 years.
Berger edged out Charl Schwartzel and Whee Kim by one.
Thornberry shot a 65 and became the first amateur to finish in the top 10 at the St. Jude Classic since 1965.
"I'm playing good. I'm confident on the greens".
His win at the following year's Emirates Australian Open at his home course at The Australian catapulted him to the verge of the top 50 in the world rankings, but it's since been a steady decline until a recent up-tick in form. She three-putted from 35 feet on the 18th and missed a 4-footer for the win. Perrine Delacour (62) and Lindy Duncan (65) were one shot back.
On Friday, Calcavecchia sandwiched four birdies around a bogey on the par-4 sixth hole, and he responded to another miscue on the back nine with a birdie putt on No. 17, a par-3.
Schwartzel looks back on track after a brief lull following his third-place finish in the Masters.
Frittelli, of South Africa, finished 12 under for the event, leading Finland's Mikko Korhonen, England's David Horsey and countryman Jbe Kruger by one stroke.