Two strokes clear with four holes remaining when the tournament was forced into a fifth day because of a thunderstorm, Els limped home with four successive pars at Bay Hill to hold off his challengers.

South African Els, who this month claimed his first tour victory in two years at the elite WGC-CA Championship, closed with a one-under-par 71 for an 11-under total of 277.

South Korea-born American Kevin Na, who trailed Els by just one with a hole to play, bogeyed the last for a 69 to share second place with Italian Edoardo Molinari, who also signed off with a 69.

"It was a tough finish for me today," Els said in a greenside interview after sinking a curling eight-foot par putt at the 18th.

"I've been thinking about these last four holes for 22 hours so it was nice to finally get on the golf course.

"I kind of limped home here today but the work I have put in started paying off, and obviously my short game is good. I got it up and down the last two holes." After early morning rain had delayed the resumption of the final round by two hours, three-times major winner Els did well to par his first hole, the 15th, after missing the green to the left with his approach.

He also found himself in trouble at the par-five 16th where he found the right rough off the tee and had to punch out a low second shot from under trees on to the fairway.

From there, he struck his third to 30 feet and coolly two-putted to save par.

Els got up and down from a buried lie in a greenside bunker at the par-three 17th to stay one stroke in front, until Na three-putted the par-four last to slip two behind.

With the tournament firmly in his grasp, Els struck a perfect tee shot down the 18th fairway but he pulled his approach left into greenside rough from where he again nervelessly got up and down to save par.

"Just to try and stay away from a lot of trouble here was tough to do," said Els, who was also champion here in 1998.

"This place tests your ability and it (winning) gives me a lot of confidence. If you win here, you can feel comfortable at majors."