Els ended his wait for a victory on American soil in Florida
(GB & Ire unless stated):
-6 E Els (RSA)
-5 L Donald
-4 N Green (Aus),
-2 B Davis
Level J Rose
Ernie Els staged a final-round comeback to beat England's Luke Donald by a stroke and claim the Honda Classic.
The South African fired four birdies on his way to a round of 67 to finish six under in Florida for his win first on American soil in nearly four years.
Donald, who shared the lead after the third day, mixed four bogeys with three birdies and failed to sink a chip at the 18th to force a play-off with Els.
Australian Nathan Green finished third, a shot adrift on four under.
"I'm so excited," said Els, whose last win in America was the Memorial in June 2004. "It's been a long time coming.
"I'm really relieved because it's been a tough ride for everyone, but ultimately you have to believe you can do it."
Donald came closest to challenging Els but could not force a play-off
When the final round began, 25 players were within five shots of the lead, which was shared by Donald, Matt Jones and Mark Calcavecchia on six under.
But Els, accompanied around the course by his sports psychologist, was the only one amongst that group to make a break after he started the day three shots back.
Els, 38, made four birdies in the first seven holes and a neat nine straight pars eventually gave him the outright lead.
He and Calcavecchia had shared the lead at the 15th but the American's shot hit a bunker and the ball rebounded onto a rock ledge across the green.
Calcavecchia tossed the ball into the water and made a double bogey to concede the lead. He ended up finishing tied for fourth.
Donald came closest to challenging Els and got within one with a birdie at the 16th then took aim at the 17th, getting the ball to stop in the fringe after a daring shot over the water.
But his birdie attempt there failed; and he again failed to hole out a birdie chip from just off the green at the last to end his hopes of a play-off and a second Honda Classic title in three years.
England's Brian Davis, who led at the midway mark, shot his second straight 73 and finished in a five-way tie for seventh.