Instead, Scott managed a 1-under 69 and is tied for the lead with Trevor Immelman, who fired a 6-under 64, after three rounds of the EDS Byron Nelson Championship. The pair is knotted at 11-under-par 199.
Brett Wetterich. who shared the overnight lead with Scott, posted an even-par 70 and is one back of the co-leaders at minus-10.
Play rotated over the Cottonwood Valley Course and the TPC at Las Colinas over the first two rounds, but shifted to Las Colinas for the weekend.
Scott flew out of the gate at Las Colinas on Saturday. He rolled in a 5-foot birdie putt at the second hole, then added an 11-foot birdie putt at the fourth.
At the par-5 seventh, Scott hit his third to 4 feet and converted the birdie putt. He made it two in a row with a 6-footer at the eighth and the young Australian built a four-shot lead.
Trouble loomed at the next tee as Scott pushed his tee shot right, where it hit a tree and fell into the water. He took a drop and hit a 9-iron 45 feet long of the hole, where he two-putted for his bogey.
Scott reclaimed the lost stroke at the very next hole, but that was the last bright spot for the ninth-ranked player in the world.
He drove into a fairway bunker at the 12th, then missed the putting surface left with his approach. Scott chipped to 7 feet, but missed the putt for a bogey.
At the 14th, Scott drove into the trees on the right again and his approach also missed on the right side. His third stopped 16 feet from the hole, but he was unable to save the par.
As Scott was sliding down the leaderboard, Immelman was heading toward the top. He recorded four birdies in his first seven holes, but parred his next four around the turn.
Immelman, who lost in a playoff last week to Jim Furyk at the Wachovia Championship, knocked his approach to 4 feet at the 12th to set up birdie. He got within one of Scott's lead at the par-5 16th, when he two-putted for birdie from 35 feet.
Scott was the one who fell into the tie at the par-3 17th. His tee ball landed in a greenside bunker and he blasted out to 5 feet. Scott missed the par putt and had a chance to take sole possession of the lead at the last, but missed from 11 feet.
'It's a little disappointing not to keep it going because I played so good on the front nine,' said Scott, who owns three PGA TOUR victories. 'I'm still in the position of leading and I've just got to hang around for a bit longer tomorrow.'
For Immelman, Sunday will offer a chance at redemption. Last week at the Wachovia Championship, Immelman bogeyed the 72nd hole to drop into a playoff with Furyk, then drove into the rough on the first extra hole and lost his chance at PGA TOUR victory No. 1.
Not that Immelman is dwelling on it.
'I felt like it was a step up for me. There were so many positives,' acknowledged Immelman. 'It would have been stupid of me to really let it get me down.'
Chad Campbell and Charley Hoffman posted matching rounds of 5-under 65 on Saturday and are part of a group tied for fourth place. Joe Ogilvie and Omar Uresti both shot 69s to join Campbell and Hoffman at 8-under-par 202.
Defending champion Ted Purdy (65), Jeff Sluman (64), Shane Bertsch (65), Scott McCarron (66), Dudley Hart (68) and Luke Donald (69) are knotted in eighth place at minus-6.
Ernie Els, No. 6 in the World Rankings, posted a 1-under 69 and is part of a group tied for 18th at minus-4. Vijay Singh, the fourth-ranked player in the world, never made a move on Saturday. He managed an even-par 70 and is in a logjam for 27th at 3-under-par 207.