Brendon Todd claimed his first US PGA Tour title with a two shot victory at the HP Byron Nelson Championship in Irving, Texas.
The 28 year old was playing in the final group of the day with fellow overnight leader Louis Oosthuizen, but, while his South African playing partner struggled to a 74, Todd kept his calm to fire a bogey-free 66 and finish 14 under.
Mike Weir finished second after a second consecutive 67, with the 2003 Masters Tournament champion showing some signs of the form that fired him into the top five in the world.
Todd began his round impressively as he holed out of a bunker for birdie on the second and he followed that with further picked up shots at five, nine and ten.
The American looked in trouble at the par three 13th as his tee shot ended up next to a tree denying him of a natural swing, but the World Number 138 played a shot with the back of a club to within seven feet and holed out for par.
Todd left himself in more trouble on the par five 16th when his third shot failed to make the green, but an excellent chip allowed him to make par and the impressive scrambling continued on the par three 17th when he rescued another par after missing the green and over-hitting his second shot.
The four on the last proved to be more routine, but Todd acknowledged that saving his par on 17 was a vital moment.
"I asked my caddie walking off the 17th tee where I was," he said. "He thought I was two up so I knew that was a big putt and I jammed it in there."
He added: "It feels amazing, a big monkey off the back. It's been a tough career so far with a lot of ups and downs but I'm excited to be on top right now."
Weir had held the lead early in the day after a blistering start with birdies at one, two four and five, but he gave shots back at six and nine.
Another bogey at 15 was sandwiched by birdies at 13 and 16 as the Canadian came up just short as he looked for a first win since 2007.
Charles Howell was two shots further back after a 67 and looked to be making a charge after pitching in for eagle on 16 and picking up a further shot on the next, but closed with a bogey.
Australian Marc Leishman was also on ten under after a 68, with James Hahn and Boo Weekley a shot further back.
Dustin Johnson, Graham DeLaet, Gary Woodland and Matt Kuchar were all on eight under, with Kuchar securing a ninth top-ten finish in 13 starts this season.
Padraig Harrington finished with a 74 in a round containing five bogeys and a double plus three birdies, one of which included an outrageous piece of misfortune.
The Irishman was 63 yards out on the par four 11th and saw his second shot bounce once before landing directly in the cup but, instead of walking off with an eagle, the two-time Open Champion saw the ball bounce out to leave him with a short putt for birdie.
Oosthuizen finished tied for 11th alongside compatriot Charl Schwartzel.
