Louis Oosthuizen birdied four of the last five holes for a 6-under 64 and a share of the third-round lead with Brendon Todd in the Byron Nelson Championship.
Oosthuizen had the low round of the day after recovering from bogeys on two of the first four holes.
Todd had a 68, making 12 consecutive pars before holing a 4-foot birdie at No. 18 to match Oosthuizen at 10-under 200.
Mike Weir, James Hahn and Gary Woodland were a stroke back at 201. Weir shot 67, Hahn 65, and Woodland 66.
Morgan Hoffmann twice fell out of the lead after hitting drives left into the water and making double bogey, at Nos. 11 and 18. He was tied for sixth at 8 under.