If Els wins Sunday - he was two strokes behind Retief Goosen and playing in the final group - and Tiger Woods finishes lower than sixth, the Big Easy takes over No. 1.
Woods was tied for 19th after shooting 73 Saturday, leaving him nine shots off the lead.
Woods has held the No. 1 ranking since August 1999, when he replaced David Duval at the head of the list.
CLOSE CALL FOR CLARK
Tim Clark was a couple of feet and an inch from the round of his life, let alone the U.S. Open.
The native of South Africa shot a 4-under 66, the best score of Saturday's third round and only one of three under par at Shinnecock Hills Golf Club. In addition to moving him onto the leaderboard - he's tied for sixth place, four shots behind leader Retief Goosen - it started conversations of what could have been.
He had a tap-in eagle on the par-5, 537-yard 5th hole and he missed a 2-foot birdie putt on the par-4 18th. A 64 would have been one shot off the Open's 18-hole record. The double-eagle would have been just the second ever recorded in an Open as T.C. Chen had one in 1985 at Oakland Hills.
It would have been the second double-eagle in a month for Clark and would have been with the same club.
'From the fairway it looked like it went in the hole, got up there and it was literally an inch behind the cup, pretty much a tap-in eagle,' he said of the 6-iron from 210 yards. 'I made a double-eagle with that club in the qualifying for this event.'
He had four birdies and two bogeys, but it was the par on 18 that kept him from really enjoying the round.
'I just hit a bad putt. It's a tough way to finish,' he said of his short run at another birdie on the final hole. 'I guess I have to put that behind me and go out tomorrow.'
Clark, who has been bothered by a sore right wrist, finished tied for ninth last week at the Buick Classic.
'I feel I've been swinging the club great and making my fair share of putts,' he said.
With Goosen leading, Ernie Els tied for second and Clark, South Africa has three players in the top seven heading into the final round. Clark is the only one of the three without an Open title.
'If he keeps his health he might win a U.S. Open,' Els said of Clark. 'He's straight off the tee, he's got good iron play. Retief, he's got the perfect temperament and a hell of a game. We've got great players coming through and it's good for the country, it really is.'
Jay Haas shot a 76 in the third round and his son Bill had a 71 leaving them tied at 6-over 216.
On Sunday, Father's Day, Jay Haas will tee off at 11:40 a.m., 30 minutes and three groups before Bill, an amateur who will turn pro next week.
'If I had made a par on 18 we would have been one group apart,' Jay Haas said. 'That would have been nice but this whole week has been something special.'
Tiger Woods had a 3-over 73 Saturday to continue his struggles in third rounds of the U.S. Open.
Woods, who has won this event twice, has broken 70 only once in the nine third rounds he has played. He had a 69 at Southern Hills in 2001, when he finished tied for 12th. The years he won he had a third-round 71 (2000) and 70 (2002).
Woods closed his round Saturday with an eagle 2 when he holed a sand wedge from 106 yards.
'I tell you what, that definitely put me back in the tournament, where if the wind blows and I play a great round of golf, I can still win this tournament,' he said.
Chris DiMarco broke his driver on Friday and said it was one of the best things he ever did.
He finished the second round using a 3-wood off the tee and missed one fairway over the final 13 holes. On Saturday, he went to a backup driver and again found the fairway nine times.
'The backup was the same as the other driver so maybe it was me and not the club,' he said after shooting a 70 that left him at 2-over 212. 'Nah, breaking that was the best thing that happened to me.'
Spencer Levin had a 1-over 71 Saturday and was at 3-over 213, the low third-round score for the four amateurs who made the cut.
Chez Reavie and Bill Haas both had 71s Saturday and were at 216, while Casey Wittenberg had a 75 and was at 217.
Three former U.S. Open champions are in the top 10 after 54 holes.
Leader Retief Goosen, who won in 2001, was two strokes in front of Ernie Els, who in 1994 and 1997, while Corey Pavin, the winner here in 1995, was tied for ninth, another four strokes back.
Els is trying to become the sixth players to win three or more Opens. Willie Anderson, Bobby Jones, Ben Hogan and Jack Nicklaus each won four, while Hale Irwin won three.
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