Bohn took control at the halfway point of the Wachovia Championship with a 5-under 67. At 9-under, he held a two shot over Anthony Kim (67). Jim Furyk, who won here in 2006, Dudley Hart and George McNeill were three strokes back after 67s.
Mickelson, ranked No. 2 in the world, drew most of the attention here with defending champion Tiger Woods home recovering from left knee surgery. But after shooting 68 Thursday in what Mickelson credited to his longer putter, he plummeted into a tie for 25th, seven shots back. His 74 included two double bogeys in the final four holes.
"There was a low round out there, and I let it slide there in the end," Mickelson said. "Unfortunately I'll have a lot of work to do on the weekend."
Mickelson will be chasing Bohn, ranked 196th and all smiles after the pressure of his future on the PGA Tour was lifted last month with a sixth-place finish at the Verizon Heritage.
Bohn injured his ribs at the Memorial last June. Doctors misdiagnosed him, and he re-injured himself later in the year. He was held to 17 events and entered this year in a precarious position. Bohn had 12 tournaments to earn $257,668 and keep his playing status for all of 2008. His strong showing at Hilton Head ended his worries.
"I'm just excited to play. I don't have a lot of pressure now that my medical status is taken care of," Bohn said. "I can just go out and free swing it."
With first-round leader David Toms struggling to a 75, Bohn shot ahead on the strength of a putter an inch longer than he's used in the past. Bohn said his coach, Mike Shannon, had been nagging him for almost two years to make the switch.
"I just didn't feel comfortable," Bohn said. "Finally I wizened up and listened to him."
Bohn needed only 26 putts, a day after he had 27.
"When you're putting well, you don't really care if you hit it to 30 feet, you really don't," Bohn said. "You're like,
'I can make this.' Then typically you don't it 30 feet, you start hitting it 12 to 15 feet, and then you start running them in.
Bohn did that at par-3 13th, when his 7-iron landed 4 feet away. He knocked in the putt for birdie, offsetting his only bogey a hole earlier.
While Mickelson's putting wasn't as sharp Friday, that wasn't his biggest problem.
With an afternoon tee time, Mickelson birdied the 10th hole to get to 6 under. He missed a birdie putt at No. 14, then strolled to the easiest hole on the course, the par-5 15th.
But Mickelson sent his tee shot into the trees. His second shot was even worse, going nearly straight left. While the ball just cleared the water, it nestled in a horrible lie of pine straw at the base of a tree.
