Jackson's 11-under 133 total includes an opening-round 66, the lowest score ever shot by an amteur playing in this event.
CARMEL, Ind. (AP) -- Tennessee amateur Tim Jackson left Greg Norman and Joey Sindelar behind Friday in the U.S. Senior Open.
The 50-year-old Jackson real estate developer shot a 5-under 67 at Crooked Stick to take the lead at 11-under 133 -- matching the lowest 36-hole total in event history. He opened with a 66 on Thursday, the best score ever by an amateur in the tournament.
Norman stumbled early in the round, but recovered nicely, ending the round with two straight birdies to get to 8 under. He was three strokes back after a 70.
Sindelar was a stroke behind Jackson. He started on the back nine and followed his course-record 66 with a 68. A birdie on No. 6 gave Sindelar a share of the lead, but he dropped a stroke on the next hole and finished the day by pulling a 5-foot birdie putt that would have tied Jackson to the left.
Fred Funk (67) was third at 9 under. He led briefly Friday before Jackson had three straight birdies on the back side. Three-time U.S. Open champ Hale Irwin was the only other player with a 67 in the second round. He was 1 over.
Jackson has been the steadiest player over the first two rounds with 12 birdies and only one bogey. He made four straight birdies Thursday and had three in a row Friday. He also consistently outdrove playing partners Jeff Klein and John Harris, routinely hit greens and putted well.
Jackson wasn't the only player scoring well on the 7,316-yard course, the longest in tournament history.
Dan Forsman (71) eagled No. 9 and birdied his final hole to go to 7 under.
Robin Freeman, who shot a 70 Thursday, made up three strokes by the turn and finished with a 68 to join Tom Lehman and Bruce Vaughn at 6 under.
Senior British Open champion Loren Roberts, former PGA Championship winner Bob Tway and 2007 Senior Open champ Brad Bryant were in a group at 5 under. Tom Watson and defending champion Eduardo Romero were 1 under.