Marco Dawson posted a four-under 68 on Sunday to move atop the leaderboard after the fifth round of PGA Tour Q School.
Dawson finished 90 holes at 17-under 343 and is three shots ahead with just one round to go in one of the most pressure-packed marathon events in professional golf.
The top 25 and ties after Monday's final round will earn PGA Tour cards for 2012. Everyone else will get some type of status on the Nationwide Tour, but that top 25 is the magic number for this massive field.
Stephen Gangluff shot a five-under 67 and is second at minus-14.
Harris English (70) and Brendon Todd (68) share third place at 13-under 347.
Will Claxton led throughout most of the first four rounds, but struggled in the fifth one. He only managed a four-over 76 and fell into a tie for fifth with former Ryder Cupper Vaughn Taylor (70), Brian Harman (68) and Jarrod Lyle (68). The group finished at minus-11.
Play rotated between the Nicklaus Tournament Course and TPC Stadium Course at PGA West throughout the six rounds. The leaders played the Stadium Course in round five and the Nicklaus Tournament Course in round six on Monday.
Dawson played great early in Sunday's fifth round. He birdied three of his first six holes to move atop the leaderboard. After seven pars around the turn, Dawson rattled off back-to-back birdies at 14 and 15.
He was at 18-under par, but a bogey at the last dropped him to 17-under par.
Dawson played the PGA Tour in years past, but he spent most of the 2011 season on the Nationwide Tour. He had three top 10s on that circuit, including a runner-up, but he made the cut in all three starts on the PGA Tour.
There are four former major champions in the field this week and none are inside the top 25.
The closest is two-time U.S. Open winner Lee Janzen, whose one-under 71 on Sunday moved him into a tie for 42nd at minus-four.