Jason Dufner beat Ernie Els in a sudden death play-off to win the Zurich Classic of New Orleans, an event which saw Luke Donald regain top spot in the Official World Golf Ranking.
Donald needed a top-seven finish at Avondale to regain pole position from Rory McIlroy - and he got it - finishing third.
However, the winner of the tournament was American Dufner, who edged out Els on the second hole of the play-off to land his first US PGA Tour title.
Dufner had not won in his previous 163 starts on the US PGA Tour and was beaten in a play-off by Keegan Bradley in last year's US PGA Championship.
Els had been a man on the move on the final day in Louisiana as he moved into a share of the lead with overnight leader Dufner.
The South African picked up two birdies and an eagle as he turned in 32, while a birdie on the 11th saw him finish on 19 under par with a 67.
Dufner followed a bogey at the sixth with birdies on the seventh, eighth and tenth to card a 70 and take the contest to a play-off - the sixth on the US PGA Tour this season.
Els had a putt of around six feet to win on the first hole of the play-off but failed to take it - and paid when Dufner rolled in from less than a couple of feet minutes later.
The 35 year old, who marries fiancee Amanda Boyd next week, said afterwards: "It was a tough day, I'd already put up a good number.
"It's been tough trying to get this first win, so this is a little bit of a monkey off my back."
For Donald, a final round 67 followed efforts of 73, 65 and 66 to see him finish two shots behind Dufner and Els.
Birdies on the third, ninth, 11th, 13th and 18th ensured the Englishman finished on his own at 17 under par.
America's Ryan Palmer and Canada's Graeme DeLaet were tied for fourth on 16 under - Palmer firing a final round 69 and DeLaet finishing with a 71.
