CARMEL, Ind. -- Here is where the leaderboard stands after 36 holes:
• With his one-stroke margin over Joey Sindelar, Tim Jackson is the first amateur competitor to hold sole possession of a second-round lead in this event since 1980 when Bill Campbell led Art Wall by one stroke in the inaugural U.S. Senior Open. Campbell went on to finish second.
• Jackson's 11-under-par total of 133 set two records on Friday. It was the lowest 36-hole total by an amateur in this event, surpassing the old record of 141 by Vinny Giles in 1994 and it was also the lowest score under par for the first 36 holes. Six players shared the mark at 9-under-par, the most recent coming in 2005 when Tom Watson, Loren Roberts and Craig Stadler posted that score. Jackson's 133 also tied the record for the best first 36 holes. Dave Stockton set the mark in 1992 and five players later matched that total.
• One of the day's biggest turnarounds was turned in by Hale Irwin. A two-time winner of this event (1998, 2000), Irwin rebounded from his opening-round 6-over-par 78 to shoot a 5-under-par 67 on Friday, an 11-shot swing. Irwin's effort helped him move from T123 to T39 after two rounds. His 67 was one of the two best rounds on Friday. Jackson also recorded a 67.
• Jim Dent (back), Scott Hoch (hand), Tom Purtzer (back) and Don Reese (back) all withdrew on Friday. Hoch and Reese had already started their rounds, while Dent and Purtzer did not start. Wayne Levi also withdrew on Friday.
• A total of 62 players made the cut at 3-over-par 147. Among those missing the cut were former U.S. Senior Open winners Allen Doyle (2005, 2006), Dave Eichelberger (1999), Peter Jacobsen (2004), Dave Stockton (1996) and Larry Laoretti (1992). Others missing the cut included Ben Crenshaw, Tom Kite, Vicente Fernandez, Fuzzy Zoeller, Lonnie Nielsen, Jerry Pate and Larry Nelson. Kite, Pate, Zoeller and Nelson are former U.S. Open winners.
• Brad Bryant leads all players in Greens in Regulation (31 of 36) and Fred Funk is the leader in Driving Accuracy (26 of 28). Dan Forsman has converted 11 of 21 birdie opportunities to lead that category. Tim Jackson and Greg Norman lead in birdies with 12. Jackson and Sindelar have the fewest bogeys with one.
• Jackson, Sindelar and Funk are the only three players in the field to have posted two consecutive rounds in the 60s.
• Current Charles Schwab Cup points leader and current money leader Bernhard Langer is T32 at even-par 144.