The Open champion pitched his nine-iron approach straight into the hole for a two - the first eagle of the tournament - to leapfrog joint overnight leader Chris DiMarco.

Els carded a superb seven-under-par 65 to lead by a stroke from the American, who posted a second successive 68.

DiMarco led for most of the second round and drew level with Els with a birdie on the 17th, only to bogey the last.

Els, who also enjoyed a birdie two on the 16th in what he described as a "crazy finish", praised his caddy Ricci Roberts for his spectacular approach on the 17th.

"That nine-iron was probably the shot of the year for me," Els said. "I brought it in from 153 metres and it just went in.

"Ricci was all over that shot and he was jumping up and down and I think the ball listened to Ricci."

Northern Ireland's Darren Clarke was the day's other big mover, a 67 propelling him into third place on his own, four shots adrift of Els.

"The course is very tough this week," Clarke said. "It's difficult to determine the speed on the greens and it makes it that little bit tougher.

"So a 67 is always good, I'm very pleased with it."