Lehmans overall 5-under-par 66 moved him to 10-under for the tournament, one shot clear of Vijay Singh (68), Billy Mayfair (68) and Billy Andrade (67).
Carl Paulson, who like Lehman started on the back nine, took just 29 swings over his final nine holes to finish off a round of 8-under 63. Hes tied for fifth place with Mike Sposa (67) at 8-under-par through 36 holes.
Paulsons 29 tied a front-nine course record set by Payne Stewart in the 1989 Tour Championship.
Lehman is seeking a bit of redemption this week after finishing runner-up to Stewart Cink at the Harbour Town Golf Links a year ago.
The 1996 British Open champion spent most of the day chasing the trio of Singh, Andrade and Mayfair, who all went out in the morning and posted the clubhouse lead at 9-under.
After playing his first eight holes in 1-over, Lehman played his next three in 4-under. He birdied the 18th, his 9th, and the 1st hole; and then eagled the par-5 2nd after hitting a 4-iron from 220 yards to within a foot of the hole.
After birdieing the par-5 5th, Lehman stuffed another approach shot on the par-4 6th to a foot and tapped in for his final birdie of the day.
I think the big thing right now is my confidence in all parts of the game, said Lehman, whose last victory was at the Phoenix Open in January 2000. Ive got the enthusiasm to want to do well and I think Im playing well.
Four-time WorldCom winner Davis Love III shot 67 to move to 7-under for the tournament, just three shots off the 36-hole lead.
Overnight co-leader Doug Dunakey enters the weekend four off the pace after following an opening 65 with a second-round even-par 71.
Singh also held a share of the 18-hole lead, and stayed in contention to win his first event since the 2000 Masters by posting four birdies and one bogey on Friday.
If you start forcing it then you are going to go backwards, said Singh, who tied for 18th last week in his Masters title defense. All you can do is go out there and play your own game, play solid shots, hit fairways and greens. Thats what I need to do.
The cutline fell at even par. Seventy-five players made the cut, including Cink, who stands at 2-under.
Full-field scores from the WorldCom Classic