This event is reserved for the 32 winners last year on the PGA Tour. Masters winner Phil Mickelson is the only player eligible for the tournament who did not attend.
Weir posted the lowest round of the day on Friday with a 10-under-par 63. He is alone at 13-under-par 133, while Ernie Els, who carded a second-round 65, has sole possession of third place at minus-12.
Jonathan Kaye and Sergio Garcia each put together rounds of 6-under 67 and are knotted in fourth place at 11-under-par 135.
Tiger Woods, who won this tournament in 1997 and 2000, could not get a putt to fall on Friday and the 663-yard closing hole was a great indication of that. He reached the green in two, but three-putted from 15 feet for a par.
'I had my chances to post a good, solid round,' said Woods, who missed six birdie putts inside 12 feet on Friday. 'We've never putted the greens this slow before. You have to make the adjustment. I'm having a difficult time making the adjustment.'
Woods finished with his second 5-under 68 in as many days. He is tied for sixth place with Ryder Cup teammates Chad Campbell and Stewart Cink, who also shot 68s in the second round, at minus-10.
Singh flew out of the gate on Friday. He drained a 10-footer for birdie at the first and knocked a 7-iron to 4 feet to set up a birdie at the 202-yard, par-3 second.
The Fijian parred three and four, but ran home a 15-foot eagle putt at the fifth to go 4 under through his first five holes. Singh birdied the sixth, then made a 60-footer for birdie at seven. The No. 1 player hit a spectacular 7-iron inside 4 feet at eight, but missed the birdie putt, starting a run of suspect golf.
He pulled his drive into tall grass at the ninth, but found the ball and made an unlikely par. Singh parred the next two holes then rolled in an 8-foot birdie putt at the 12th.
Singh parred the next five holes. He failed to find the green with his second at 18, but chipped to 6 feet and converted the birdie putt.
'I played well,' said Singh, who is the only player in the field without a bogey. 'I didn't make too many mistakes. The putts kind of dried up on the back nine, but I made a lot on the front.'
Singh overcame a missing driver on the range to match the third lowest score in the second round. After nine wins, the money title and Player of the Year award in 2004, Singh is confident he can continue his run into the weekend.
'I'm looking forward to. I'm putting well and playing well,' said Singh. 'I made my share of putts out there and hopefully I'll have another one tomorrow.'
Weir, the 2003 Masters champion, broke into red figures with a 5-foot birdie putt at the par-3 second hole. He made it two in a row at three, then recorded back-to-back birdies at five and six. The Canadian drained a 10-footer for eagle at the ninth to make the turn at 6-under-par 30.
'I got off to a great start,' admitted Weir, who won last year's Nissan Open to get into this field. 'After I made that eagle on No. 9, I was 6 under at the turn. I felt like I had something special going.'
Weir bogeyed the 10th, but rebounded with a birdie at No. 11. He birdied the 14th, then went on a run that vaulted him into second place. Weir sank a 12-foot birdie putt at 16, holed a 35-foot birdie putt at 17 and closed with his third birdie in a row to trail Singh by only two.
'I wasn't expecting to shoot that low of a round because I haven't been playing,' said Weir. 'I've been off for seven weeks and haven't been playing any golf at all. Practicing quite hard but not playing. Just nice to see some nice putts go in and I hit the ball pretty well today.'
Stuart Appleby, the defending champion, got back into the mix on Friday. He fired a 9-under 64 and is part of a group tied for ninth place. Reigning U.S. Open winner Retief Goosen (67), former PGA Champion David Toms (67) and Vaughn Taylor (69) joined Appleby at 8-under-par 138.
Craig Parry, who was alone in second place after an opening-round 67, struggled to a 1-under 72 and is now tied for 13th place at 7-under-par 139.