Masters champion Mike Weir, who bogeyed his last two holes en route to a 1-over 71, joined Billy Andrade, who started the week as an alternate, in second place at 1-under-par 139. Andrade went off in the morning and carded a 2-over 72.
Micheel was 1 over par when he reached the fifth hole, his 14th on Friday. He knocked a 9-iron to three feet to set up birdie and reach even par, but the best was yet to come for the Memphis resident.
At the par-3 sixth, Micheel tried to play a 6-iron to the middle of the green but instead knocked it to 20 feet and sank the putt to match Weir and Andrade in first place at minus-1.
Micheel parred the seventh, then took sole possession of the lead at eight when he played a 9-iron to 25 feet and drained the putt. He added an eight-footer for birdie at the ninth to take a two-shot lead in only his first trip to the PGA Championship.
'I'm kind of glad the day is over and I'm certainly glad the way I finished,' said Micheel, who has three top-10s on the PGA Tour in 2003. 'I was just really happy and really honored to be invited. I wasn't really watching the leaderboard. I was really more concerned about keeping myself in position so that I might have a good weekend.'
Rod Pampling, one of the overnight co-leaders, holed a 9-iron from 148 yards for par on the 18th hole to shoot a 4-over 74 and stand alone in fourth place at even-par 140.
Phil Mickelson, who shared the lead with Pampling on Thursday, had things going with a birdie at the fourth hole to reach 5 under par. It unraveled from there as Mickelson drove into the rough at the fifth, then dunked his second in the water. He left the hole with a double bogey but still held the lead.
Mickelson, who is 0-45 in major championships, splashed his tee ball on the seventh and played his third at the par-4 hole to the collar of the fringe behind the green. He pitched to 10 feet and missed that putt for his second double bogey in three holes.
The left-hander bogeyed 14 and 17 for a round of 5-over 75.
'The difference today was that I did not offset those mistakes with any birdies, whereas yesterday, the couple of bogeys that I had, I made six birdies to offset it and I had a good round,' said Mickelson, who finished second in this event to David Toms in 2001. 'I thought the biggest difference for me today was actually, well, two things. When I missed the driver, it was to the right, which is not good for me and the second thing was, I didn't make any putts.'
Mickelson is part of a group in fifth place at 1-over-par 141 with three-time major winner Ernie Els (70), Chad Campbell (72), Jose Coceres (68), Tim Herron (72), Adam Scott (69) and Tom Pernice, Jr. (71).
Tiger Woods, the winner in 1999 and 2000, will have his work cut out for him if he is to earn his first major title of 2003. He followed up his first-round 74 with a 2-over 72 and is tied for 39th at 6-over-par 146.
He bogeyed two of his final three holes with wedges in his hands from the fairway.
'I thought I hit good shots, but didn't hit it close and that's disappointing,' said Woods.
With Woods safely in the rear-view mirror, Micheel now only has to worry about the Oak Hill Course, some major winners within striking distance and an untested track record in major championships.
'Surely, I'd love to add my name to the long list of names that are on that Wanamaker Trophy, but that's obviously getting a little bit ahead of myself,' said Micheel. 'I haven't really proven myself as a tour winner yet.'
Micheel looked like an ordinary tour player when he double bogeyed the 14th after a poor approach and a poor chip. He bogeyed the 15th when he three-putted but reclaimed the stroke with a birdie at 16.
He saved an amazing par at 17 when his drive landed in the right rough. He left himself with close to 50 feet to save par and poured it in for what Micheel called the turning point of his round.
Micheel birdied 18 but dropped a shot at three. Then came the big finish and now, the final pairing in a major championship awaits.
'I don't see any reason why tomorrow will be any different,' said Micheel. 'I mean, it probably will be, but if I keep hitting the fairway, there's no reason why I can't have another good day tomorrow and even Sunday.'
Weir had control of the championship at 3 under par but stumbled into the clubhouse. He finished on the front nine Friday and missed a four-footer at No. 8. At the ninth, he missed the fairway on the right, then pitched out into the left rough and missed the green short with his third. He got up and down from there and had to settle for a joint second.
'It wasn't the finish I was looking for, but that's this golf course,' said the Masters champion. 'You miss a shot a little bit off-line, it's going to bite you.'
Andrade would have been alone in second place had he not missed the fairway on eight, his 17th of the day. He left with bogey and posted the lowest total in the clubhouse after the morning tee times.
'I know one thing, when they see my name on the leaderboard at 1 under, I don't think they are scared,' said Andrade, who made it in this week when Larry Nelson withdrew. 'I don't think there's anybody scared that Andrade is up there. We'll just have to wait and see what happens. I played the best that I could play for two days and I can't wait till tomorrow.'
The 36-hole cut fell at 8-over-par 148 and several top-ranked players failed to survive the weekend. Thomas Bjorn, Darren Clarke, Davis Love III and Sergio Garcia all finished at plus-9; Retief Goosen was 11-over par and 2002 champion Rich Beem posted a two-day total of 17-over-par 157.