It's hard to escape the feeling that something sinister is afoot in the Oklahoma hills. Apart from the intrusive thunderstorm on Thursday that wrecked all the best-laid plans, and Tiger Woods' disastrously timed glitch in form, there's also the gathering that has assembled atop the leader board. As the 101st US Open here at Southern Hills Country Club sought, apparently in vain, to find some sense of order yesterday, some unexpected names contrived to shove the sport's heavyweights out of the way.

JL Lewis, a 40-year-old journeyman professional did it. So too Retief Goosen, who has been largely an anonymous figure on the European Tour this season. And Mark Brooks, who hasn't won since achieving a career highlight in capturing the US PGA title in 1995, also managed to scale the heights. All three contrived to claim the clubhouse lead on four-under-par 136 of an uncompleted second round that didn't quite catch up with the residue of the previous day's storm.

While almost two-thirds of the field answered early-morning alarm calls to complete their first rounds, they found quite different conditions. The dark clouds and forked lightning had been replaced by clear blue skies with little wind and the greens firmed up to ensure that the course became a true test with an added emphasis on approach play and putting.

For some, it was a long, hot day at the office. But, as David Duval, who had to play 25 holes yesterday, explained, "It's a small price to play to have a chance to win the US Open." Indeed, Duval was one of the bigger names to show his intent as a birdie on his last hole gave him a 69 for one-under-par 139 to make the leading trio look over their shoulders.

Also lurking with intent of their own were Phil Mickelson, who holed-out for an ace with his eight-iron tee-shot at the 175 yards sixth, to move to one-under with four holes left of his second round while more serious inroads were made by Davis Love and Sergio Garcia, who had moved on to the two-under mark as they neared the conclusion of their rounds.

As lengthening shadows gathered, the two Irish players in the field - Padraig Harrington and Darren Clarke - were constructing solid rounds. Harrington turned in 35 but suffered a bogey at the par five 13th to be on four-over, while Clarke was level par for his round, and also four over, after eight holes. In the fifth last group left out on the course, Clarke will be due an early-morning alarm call today in order to finish his round.

With the three leaders on four-under, it is anticipated that the 10-shot rule will come into effect - and the anticipated cut to be six-over - all of which doesn't concern Goosen.

Goosen, who completed the final 11 holes of his first round in the morning dew to join Hale Irwin and Mike Weir as first round leaders on the 67 mark, was the only one of the three to maintain that form in the later heat of the day. Irwin slipped away when covering the opening nine holes of his second round in 41 strokes, while Weir signed for a second-round 76. In contrast, the South African played solidly to record a level-par 70.

Playing alongside Lewis, who had a second 68, the big play of the day came from Brooks, who took advantage of near-perfect golfing conditions to leapfrog through the field. Recording a score that tied the lowest second-round score in US Open history, Brooks, without a win in six years and with only one top-10 finish this season, had six birdies on his way to a 64.

The secret, it seems, was a new driver that he put in his bag during the 40 minutes break he had between finishing his first and starting his second round. "I wasn't happy with the one I had, so I sent my wife back to the house to get a different one and proceeded to hit the first two fairways," said Brooks. More than that, he managed to hit some decent approach shots: a six-iron to 12 inches on the first, a four-iron to 12 feet on the second. He reached the turn in 30 and, fireworks over, added a solitary birdie, on the 11th, to eight pars on the homeward run.

As someone who has won a major, Brooks can expect to shoulder most of the expectations over the final two days. "I think it used to be more that way in the past, that if you were a major winner it would be an advantage. It's not so much that way any longer. Most of the guys are pretty seasoned and they realise someone is going to win . . . and then there is always Tiger. He's probably shown that he is human this past two days and, if I can shoot 64, then he can come out and shoot 60. Don't count him out."