A strangely vulnerable course suddenly regained its teeth in the wind and heat of the afternoon, as Payne Stewart remained top of the leaderboard in the 98th US Open here at the Olympic Club yesterday. But the former champion had a nervous three-putt finish for a 71 and a halfway total of 137, one stroke clear of Jeff Maggert and Bob Tway.

Darren Clarke got through on 146 - six over par - and the cut on which the leading 60 competitors and ties survived, was expected to be 147, the same as in the last staging here 11 years ago. Padraig Harrington, a late starter who shared 35th place after an opening 73 on Thursday, improved that position with an impressive outward journey of 34.

Pre-round tension was quickly eased for the Dubliner with a birdie at the long first and though he dropped a stroke at the fourth for a second successive day, amends came soon afterwards. He birdied the seventh and sank a 30footer for an improbable par at the eighth to be two over par for the championship. And after dropping four strokes on the inward journey he finished with a birdie for a 72 to qualify comfortably on 145.

Overcast skies and overnight fog dampened the greens more than the USGA would have liked for the morning's play. But, typically, they found ways of maintaining the pressure on an elite field. For instance, even more water was added to the 18th and the pin was placed 18 yards back, on the top slope.

It meant that any player who was brave enough to shoot all the way to the flag, could expect his ball to grab the receptive surface and then come spinning back down the green. A wicked mousetrap had been set for sophisticated mice.

Stewart fell for it by failing to keep a 12-foot birdie putt above the hole. The result was that the ball turned down the slope, rolling and rolling until it finished 25 feet away from where he took two more to get down.

It wasn't the only interesting action on the 18th. Tom Lehman, who had taken three putts from within four feet of the target at the 10th on Thursday, experienced similar grief, four-putting the last for a double-bogey six. No sight was more appealing, however, than that of 57-year-old Jack Nicklaus finishing with a birdie, all the way up the slope.

It seemed that the ball was stuck, stubbornly on the lip for an eternity before it dropped, prompting the great man to throw his arms into the air in delight. "I felt I needed a birdie to make the weekend and I get I willed the ball in from 40 feet," he said afterwards.

A round of 74 gave him a total of 147, which was very much on the borderline. But it was as if he never doubted his ability to survive. "I don't know if I do it very well any more, but I love playing this kind of golf," he added, with obvious conviction.

Defending champion Ernie Els found a different route towards survival, as he followed a dispiriting first round of 75 with a sparkling 70. Determined not to blame Thursday's struggle on recent back problems, he seemed destined for an early departure when reaching the turn in 38 - three over par.

That was when he got the break he desperately needed - by holing his short-iron approach for an eagle-two at the 422-yard 10th. A birdie at the short 15th, then made his position safe. But there was no boost for the Murphy's Irish Open in the performance of Nick Faldo who cannot seem to find a way out of what has become a lengthy slump.

Though he fought back for a 72 after three successive bogeys at the third, fourth and fifth, the damage had been done in an opening 77. He finished on 149, the same score as the 1996 champion Steve Jones. Among the more notable challengers even further back were Steve Elkington (150), Bernhard Langer (153) and Ignacio Garrido (154).

Meanwhile, the crisp iron-play of Nick Price swept him into contention with a splendid 68 for 141. Yesterday's round contained five threes in an outward 32. And three of them came in the first three holes where he carded eagle, birdie, par. "After yesterday's frustration, I'm really happy with the way things went today," he said.

As Els experienced on the 10th, Price's eagle was a real tonic insofar as it resulted from a holed pitch of 25 yards. And he promptly rode his luck by holing a 15-footer at the next for a birdie.

While watching one of his playing partners, Jeff Maggert, have quite a fruitful day on the greens for a 69 and for a share of second place, Clarke found the target to be decidedly elusive. But there were still some useful, saving putts, notably an eight-footer for a par on the delightfully tricky seventh, which has been a source of considerable torment.

He had already dropped his first stroke of the round at the fifth, which he three-putted, sending his first effort five feet past. Then came a badly hooked tee-shot into trees at the seventh where he had to punch a low recovery which ran through the green. This was followed by a recovery chip and a saving eight-footer.

But there was a particularly painful miss at the difficult ninth where his ball-striking totally overshadowed the efforts of Maggert and the other member of the three-ball, Phil Mickelson. After a glorious approach iron finished five feet below the hole, Clarke missed the birdie putt.

Despite a damaged toe in his left foot - the right or pivoting foot would have been more serious - he continued to hit some masterly shots on the homeward journey, without the desired response from his putter.

In these circumstances, it was a body-blow to bogey the 17th where, finding himself between clubs for an uphill shot of 175 yards, he chose a five iron which flew too far and came to rest in the back bunker. "With a few breaks on the back nine, I would have been almost in the tournament," he said afterwards. "Now I have huge ground to make up."

Clarke added: "I'm just not sinking enough putts. I had six chances inside 15 feet and missed them all. To got to be sinking a fair share of those to compete at this level."

While many others suffered, Matt Kuchar went smiling through, just as he had done when finishing in a share of 21st place at Augusta National two months ago. And he is going to delight a lot of American mums by appearing in the last round of the US Open on his 20th birthday tomorrow.

US Amateur champion last year, he followed an opening 70 with a similarly consistent 69 yesterday to be only one stroke off the early lead on 139. Had he aspirations about winning? "All I wanted was to have a great time and here I am one under for the championship," he said afterwards. "I'm surprised and delighted."

Even when he talked of a "disastrous" bogey at the 14th, the cute smile never left his boyish face. This was serious American pie which would have had cynical Irish youngsters screaming for someone to pass the bucket. But they all love Matt over here. Indeed Johnny Miller actually tipped him for the title.

There was a far more serious response from the reigning British Open champion, Justin Leonard, after a 75 that contained a run of double-bogey, bogey, bogey, from the 15th to the 17th. In fact he four-putted the 15th where, by his own admission, he hit his first two putts too firmly.

Leonard, who was playing with Kuchar and Els, said: "I didn't do anything very well today. I was simply concentrating on holding it together." For many, the Leonard way represented the only route to towards possible survival.