Ben Crane leads by one shot at the AT&T Byron Nelson after carding a second-round seven-under-par 63 on Friday, but world number two Jordan Spieth is nipping at his heels.
Crane, who is ranked 405 in the world, moved one stroke ahead of the pack after shooting eight birdies and a solitary bogey, which came on the eighth hole.
Two-time Major winner Spieth is one of four golfers in the field who are just one shot behind Crane on 11-under-par for the tournament.
The 22-year-old managed to claim just one birdie on the front nine, but he ramped up the pressure on the top after the turn by scoring five birdies and suffering just one bogey.
The overnight leader Sergio Garcia dropped one shot behind following a four-under-par 66 round.
