Jason Day overcame a wayward performance from the tee to retain a share of the lead heading into the final round of the WGC-Bridgestone Invitational in Ohio.
Day hit only three of 14 fairways, and one of those was via a kindly deflection off a marshall's foot on the final hole, but he still managed to grind out a one-under 69 to join Scott Piercy at the top of the leaderboard on five under par.
Piercy kept a bogey off his card until a poor drive at the last turned a 66 into a 67, while US Open champion Dustin Johnson made a significant move as a superb 66 - the low round of the day - moved him within three of the leaders.
Johnson had started the day on two over after an erratic 73 on Friday, but he hit his stride on the front nine as he carded four birdies in six holes from the fourth to cruise to the turn in 31.
The world No 3 gained further ground when he rolled in a monster 45-foot putt for birdie at the 11th, but his momentum stalled when he blocked his drive into thick rough at the 14th and could not avoid dropping his first shot of the day.
Johnson parred in to claim the clubhouse lead on two under, but he was soon surpassed by a stroke when Brian Stuard handed in a 67 featuring five birdies and two bogeys.
Piercy got off to a hot start when he holed his bunker escape for an unlikely eagle at the second, and he parred the next nine holes before almost holing his 117-yard approach to the 11th.
The Oakmont runner-up jumped into the outright lead with another birdie at 17, but his error at the last resulted in his only blemish of the day as he closed on five under par.
Day looked on course to open up a commanding lead when he holed from 15 feet for an opening birdie, and he nailed a putt from similar range at the sixth before giving both shots back over the next two holes.
His errant driver continued to cause problems after the turn, but he holed a series of clutch par putts and got back to five under with a superb 35-foot putt for his third birdie of the day at the short 15th.
The world No 1 missed a chance to claim the outright lead from 12 feet at the last, while David Lingmerth ended the day a shot off the lead after offsetting four birdies with three bogeys, including a scrappy six at the long 16th - a hole which proved a card-wrecker for a number of players throughout the round.
Jordan Spieth was the highest-profile casualty when, having got to three under for the tournament with birdies at the 11th and 14th, he came up short with his third to 16 and his ball hit the front bank and rolled back into the water.
His fifth flew the green and nestled in the dense rear rough, from where he almost pitched back into the hazard before two-putting to walk off with a triple-bogey eight.
To his credit, Spieth responded by rolling in a 25-foot putt for birdie at the 17th, although he gave the shot back at the last to post a disappointing 71 which leaves him five behind Day and Piercy on level par.
Spieth's close friend Justin Thomas also found water with his third shot at the 16th as he ran up a seven to slip to one under, while 2011 Masters champion vaulted up the leaderboard with five birdies on the back nine, although he also bogeyed the last to post a 67 - two under for the tournament alongside Johnson and William McGirt.