There was a fog delay that took up almost three hours on Friday. Players were unable to see in front of them, but play resumed. Twenty-three groups will return to Torrey Pines Saturday at 10:30 a.m. (ET) to complete the second round.
Lehman posted his 67 on the more difficult South Course. Players rotate between the North and South Courses over the first two rounds before the final two are contested at the South Course.
Peter Lonard of Australia is alone in second place at 12 under par. He is 7 under in his second round, but has one more hole to play Saturday morning.
Tiger Woods is in third at minus-11. The three-time former champion is 8 under through 17 holes at the North Course and happy to be where he is in the tournament since he battled the flu earlier this week.
'I'm feeling better, feeling stronger, I just don't have my energy back or my stamina, because I lost so much weight so fast,' said Woods. 'It's going to take a little time before I put that weight back, but I'll take right where I'm at.'
Woods is ahead in the battle of the 'Big Four,' as Retief Goosen is the only player ranked in the top-5 in the World Rankings not on hand this week.
Ernie Els, the third-ranked player in the world, carded a 1-under 71 at the South Course and is part of a group tied for eighth place at 8-under-par 136.
Phil Mickelson, No. 5 in the rankings, improved in the second round of his 2005 season debut. He fired a 5-under 67 and the reigning Masters champion moved into a tie for 20th at minus-5.
Vijay Singh, the top player in the sport, continued his struggle in this event. Last year, Singh missed his only cut here, and on Friday, he is 2 under par with one hole to play at the North Course. He stands at 3 under for the tournament.
For the second consecutive day, Lehman upstaged those ranked ahead of him.
He opened on the back nine at the South Course and birdied the 11th from 15 feet. Lehman three-putted the 12th from 70 feet for a bogey, but rebounded with a two-putt birdie at the par-5 13th.
Lehman parred out until the first when he tallied back-to-back, 12-foot birdie putts at one and two. He dropped shots at three and five, but closed out his round in similar fashion to Thursday's opening round. In the first round, Lehman rattled of six straight birdies to close, but on Friday the number was less with a slight interruption in between.
He missed the green left with his second shot at six, but chipped to a foot and tapped in for birdie. The Ryder Cup captain knocked a 5-wood to 15 feet to set up birdie at seven. Before he reached the green to hole his birdie putt, the horn sounded, but Lehman was not complaining.
'I felt the fog delay actually worked in my favor,' admitted Lehman. 'I was struggling a bit with my swing, and thought the break actually helped me out. I went to the range and hit balls for an hour and a half, and felt like I kind of got back on rhythm again.'
Lehman definitely got back into rhythm. At the par-3 eighth, Lehman hit a 7-iron to 5 feet and sank the putt. He closed his round with a fourth consecutive birdie when he drove in the rough, but pitched out and hit and 8-iron to 15 feet.
'I putted very well,' said Lehman, who matched Lennie Clements 1996 36-hole record of 129. 'I didn't hit the ball all that well, it was streaky, at best. I made my share of bogeys, I made eight birdies. So when I hit it close I took advantage of it.'
Kevin Sutherland (66) and Dudley Hart (69) share fourth place at 10-under-par 134.
Luke Donald, who lost in a playoff last year to John Daly, shot a 5-under 67 and is tied for sixth place at 9-under-par 135. Dean Wilson is also at 9 under par as he is even on his round through 12 holes at the South Course.
Arron Oberholser (72), Scott Hend (64) and Aaron Baddeley (70) are tied with Els in eighth place at minus-eight. Tom Gillis and Pat Perez are 8 under and will have to finish their second rounds on Saturday.
Daly posted a 2-under 70 and is in at 2-under-par 142, which is currently the cut line.