A last-hole double bogey from Michael Letzig handed control of the Buick Open to Tiger Woods in Michigan.
World number one and two-time Buick Open winner Woods began the day in a tie for fifth place, four shots behind Australia's John Senden.
Senden's second-round 66 had left him topping the halfway leaderboard at 14-under-par, two shots clear of American Letzig at the 7,127-yard par-72 Warwick Hills Golf and Country Club in Grand Blanc.
A 71 from Senden allowed Letzig to take charge before a poor greenside bunker shot at 18 led to a six on the par-four closing hole for a third-round 68, leaving Woods, who had earlier completed a seven-under 65, with a one-shot lead heading into the final round.
Woods, who rebounded from an opening 71 with a 63 yesterday, will start the fourth round at 17-under-par, one clear of Letzig, with Senden at 15-under.
Americans Matt Bettencourt and Vaughn Taylor were tied for fourth at 14-under while compatriots Charles Warren and Jimmy Walker held a share of sixth place with Australian Greg Chalmers at 13-under.
Woods had started strongly with birdies at the second, third and fourth holes before a bogey slowed his progress at the par-three eighth as he went out in 33.
Although four birdies on his inward nine of 32 represented a better return, the world number one said he was happier with his front nine.
"Today was a scoring day," Woods said. "I hit it good on the front nine, on the back nine I hit some loose shots and was just scrambling and trying to keep pace because those guys were just making birdies everywhere."
Two of Woods' birdies at the par-five 13th and 16th holes typified the scrambling effort following errant tee shots, while his par on the par-four 18th was achieved despite bunkering an approach shot from the tree-lined 10th fairway.
"Well, you're not supposed to be doing that," he added. "You know, this golf course is pretty short. So you have to take advantage of the holes, and I did that, but unfortunately I didn't do it the correct way."
He joked: "It was on the fairway - someone else's fairway - twice on the back nine. So it was an interesting back nine, but I came out well."
There was a seven-way, all-American tie at 12-under with Scott Piercy shooting the low round of the day, a 64, while Ben Crane and Woody Austin got there posting 65s and Bob Heintz a 66.