Chris Riley fired a 7-under 63 to join Willie Wood in a tie for second at 10-under-par 200. Kenny Perry, who has three victories to his name in 2003, was one shot further back at 9-under-par 201 along with Craig Barlow.
Jacobsen carried a one-shot lead over fellow veteran Jay Haas into the third round at the TPC at River Highlands. Jacobsen had a slow start with four straight pars before finding trouble with a bogey at the par-3 fifth but managed to recover with a birdie at the par-4 seventh.
Jacobsen, who won this event in 1984, found trouble again on the inward half with a bogey at the par-3 11th. He countered with a birdie at the 13th but dropped another shot with a bogey at the 14th.
The 49-year-old missed the green with his drive at the par-4 15th but chipped to three feet for a birdie. At the 16th, Jacobsen ran home a long birdie putt to make it two in a row and despite his earlier struggles, he still found himself at the top of the leaderboard.
'On a Saturday or any round on the tour, you're inherently aggressive, so you are always hitting at the pins and end up leaving a lot of little teeny chips and putts off the fringe,' said Jacobsen. 'So the days of hitting the ball to the middle of the green, just to try to make par out here are over.'
Wood was one of the players who made early runs to surge into the lead throughout the round on Saturday. He opened with three birdies over his first nine holes and picked up back-to-back birdies from the 11th to reach 13-under.
After a bogey at the 14th, Wood still held a two-shot lead over the field. Everything fell apart for the 42-year-old at the short par-4 15th, however.
Wood went for the green off the tee with a driver but was unlucky and found the water. What resulted was a triple-bogey 7.
'After some name-calling, I just tried to relax a little bit and play the rest of the holes,' said Woods. 'I hadn't been in that position very much lately and controlling adrenaline, tempo of my swing is probably something that I need to be aware of.'
Wood recovered with a birdie at the last for a round of 68.
Riley, who captured last year's Reno-Tahoe Open, got off to a good start with three birdies on the outward nine. Riley then drained a 12-foot putt for a birdie at the 10th and hit a 9-iron to five feet at the 12th for the first of three consecutive birdies.
'I have been playing good all week,' said Riley. 'I played well last August and I am getting ready for a nice stretch of tournaments that I love to play in.'
Perry tallied a pair of birdies to go along with a bogey on his front nine to make the turn at 7-under. He bogeyed the 12th but countered in style with an eagle at the par-5 13th.
At the 15th, Perry drove the green at the short par-four. His tee ball stopped two feet from the cup for a tap-in eagle to move the 42-year-old to 10-under.
Perry struggled soon after with back-to-back bogeys starting at the 16th but picked up a birdie at the closing hole for a round of 67.
'Any time you are within two or three of the lead, you are in good shape,' said Perry. 'If I can just get my irons to come to me, just a little bit, where I can get comfortable, be a little more aggressive, and aim at a few more flags, I will have a good shot tomorrow.'
Darron Stiles, Robert Damron and J.J. Henry finished three shots off the lead at 8-under-par 202.