Mickelson, who also won this event in 2002, shot an 8-under 64 at La Quinta Country Club on Thursday, while Jacobson fired a 10-under 62 at Bermuda Dunes. The duo is knotted at 14-under-par 130.
The format for this five-day tournament is a pro-am as one professional plays with three amateurs. They split the action over four courses (the Palmer Private Course at PGA West, Bermuda Dunes Country Club, Tamarisk Country Club and La Quinta Country Club) throughout the first four rounds, then play the Palmer Course on Sunday.
Robert Damron, one of five co-leaders after Wednesday's first round, carded a 5-under 67 at La Quinta and is tied for fourth place at 13-under-par 131. Fred Couples shot a 66 at La Quinta, Billy Mayfair and Peter Lonard each posted 64s at Bermuda Dunes and Jason Allred carded a 65 at Tamarisk to join Damron four shots out of the lead.
Ogilvie, who posted two top-3 finishes in the 2004, hit a pair of poor shots on the first hole, a par-5, but sank a 15-footer for birdie. He lipped out three birdie putts in his next four holes, but drained a 12-footer for birdie at six.
His birdie putt at was a 'vicious lip out,' but the four-time winner on the Nationwide Tour bounced back. Ogilvie knocked it inside 2 feet to set up birdie at eight, then even closer at nine to make the turn at 4-under-par 32.
Ogilvie continued the fine streak around the turn. His third birdie in a row was also a tap-in at the 10th, then Ogilvie ran home an 18-foot birdie putt at 11 for his fourth in a row.
At the par-5 13th, Ogilvie converted a 4-foot birdie putt to reach 15 under par for the tournament. He got to minus-16 with a 3-foot birdie putt at 16, but found his first trouble of the round at the par-3 17th.
Ogilvie missed the green and hit a bad chip. He left with bogey, but closed his round in style. Ogilvie had 220 yards to the pin at 18 and elected to hit a 5-wood. His ball stopped 5 feet from the hole and he rolled in the eagle putt to miss the 36-hole tournament record by a shot.
'I played well, hit it close, and made the right putts, which you have to do when you shoot 63,' said Ogilvie, who tied for second at the 2004 event in New Orleans. 'It's a place that you can go low, and hopefully it can continue.'
Ogilvie held a piece of the 36-hole lead at the 2001 Greater Hartford Open, but he knows this week is a completely different deal. Players must go low in this five-round tournament, and Ogilvie is ready for the challenge.
'When you have the lead here, it's kind of a false lead,' admitted Ogilvie. 'You literally saw Duval's 59. Unless you're up by 18, which is almost impossible, no lead is safe here.'
Mickelson, who defeated Skip Kendall in a playoff last year, tallied three birdies on his opening nine. He made back-to-back birdies at 10 and 11, then collected his sixth birdie of the round at the par-five 13th.
The reigning Masters champion used two birdies in a row from the 15th to get into a share of second place.
'I had a great time,' said Mickelson, who made his 2005 season debut last week at the Buick Invitational. 'I won't know how I stand in the tournament until after Saturday. I know the scores will be low. I'm going to need to play extremely well to keep myself in contention.'
Jacobson flew out of the gate on Thursday with four consecutive birdies from his second hole, the 11th at Bermuda Dunes. He added birdies at 16 and 18 to make the turn at 6-under 30.
Jacobson birdied one and two, then closed with birdies at eight and nine to post his lowest round on the PGA Tour, besting the 64 he shot three times last year.
'I just played really solid,' said Jacobson. 'I had a good stretch of birdies and then I went dry for a couple of holes, but I finished strong. I gave myself a lot of chances.'
Joe Durant, who established a new PGA Tour record in relation to par at 36-under when he won here in 2001, carded a 6-under 66 at La Quinta. He is tied for eighth with Tim Herron, who shot a 64 at the Palmer Course, and first-round co-leader Ted Purdy, who posted a 68 at La Quinta. The trio is knotted at minus-12.