After Els tied him with a birdie at the 17th hole, Lehman, the 1997 winner, needed a birdie at the final hole to win or a par to force a playoff. But he pulled his drive into the water of Rossdhu Bay.
In the 1997 U.S. Open at Congressional, Lehman bogeyed the 16th to fall a shot behind Els, then hit his shot into the water on the 17th.
On Saturday, Lehman's errant tee shot led to a bogey and put him in second, a stroke ahead of defending champion Colin Montgomerie, who also bogeyed the last hole.
Montgomerie's $103,000 in earnings, made him the first European to go beyond $15 million for his career.
Notah Begay III, who began the final round tied with Els and Lehman for the lead, faded to a 72 after a double bogey at the 16th and shared fourth with South African Retief Goosen and Stephen Allan of Australia. Begay was shooting for his third straight tournament victory.
Phil Mickelson had the day's best round, a 65 which left him tied for seventh with Jarmo Sandelin of Sweden. They were ahead of halfway leader Nick Faldo, who dropped three shots on the first two holes to fall from contention and finished with a 73.
In the final tuneup before next week's British Open at St. Andrews, Els' 7-foot birdie putt at the 205-yard par-3 17th proved the decisive stroke.
"This is quite special. At times today I played brilliantly, at other times I was very ordinary," Els said.
"The key was hanging in there, saving par at the 14th to the 16th and at the 18th. To win these things you have to make the par saves and I had no bogeys on the back nine."
Els, who also won the 1994 U.S. Open, looked like he might be throwing away his chance when he three-putted from four feet for a bogey at the 7th hole. Then at the short 8th he hit his 8-iron tee shot into a bunker and took another bogey.
He got those shots back with birdies at the 12th and 17th and that proved to be enough.
"This is the best course in Europe and I'll be coming back every year before the Open championship," Els said.
Lehman, the 1996 British Open winner, said he was not surprised by his final drive.
"It was disappointing but I was fighting my swing the whole week. Normally when you do that it bites at the wrong time," he said.
"My swing is just not doing what I am expecting it to do at times."
Montgomerie, who has never won a major title despite being world-ranked No. 3, likes his chances at St. Andrews even though he has missed the halfway cut at five of his last eight British Opens.
"This is the best I've felt going in. I feel really good about things now," he said.
©2000 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed