Australia's Marc Leishman and American Aaron Wise share a four-shot lead over the rest of the field heading into the final round of the AT&T Byron Nelson in Texas.
A three-putt bogey on the 18th cost Wise what would have been a one-shot advantage after he completed a three-under-par 68 to sit 17-under at Trinity Forest Golf Club in Dallas.
Leishman - who produced a stunning opening round 61 - signed for a 69, recovering from a bogey on the second hole to sink successive birdies at 14 and 15 as he battled with the American for the outright lead as conditions turned more windy.
.@MarcLeish puts himself in position to tie for the lead at the last.#QuickHits pic.twitter.com/GM6NYidSwk
— PGA TOUR (@PGATOUR) May 19, 2018
Wise, meanwhile, dropped two shots on the front nine, where he also picked up four strokes before the turn.
The 21-year-old, chasing a first PGA Tour victory, looked set to finish the third round holding a narrow lead following back-to-back birdies on 16 and 17, only to then lose composure at the 502-yard final hole.
Leishman's compatriot Matt Jones climbed up four places on Saturday into a tie for third with Kevin Na (69) on 13 under after his 68 left him four shots adrift of the leaders, having also made a bogey at the 18th.
Charles Howell III was the biggest mover, some 44 spots, with his blemish-free six-under 65 leaving the American in a group of players tied for 11th at 10 under.
World number three Jordan Spieth was struggling to make an impact on his home-town tournament, the Texan shooting an even-par 71, which included three bogeys, to be tied for 29th on seven under.
Brian Gay, meanwhile, sits in a tie for fifth place at 12 under following a round of 72 - which saw one of his drives casually picked up and then swiftly put down by a spectator, the man wearing flip flops and having a drink, as the ball rolled off the fairway into sand towards a concessions stand.
