South African Rory Sabbatini held off a charging Tiger Woods to retain the outright lead in the WGC-Bridgestone Invitational third round.
Two strokes clear at the start of another gruelling day at Firestone Country Club, Sabbatini carded a two-over-par 72 to finish one ahead of five-times champion Woods.
Sabbatini shrugged off a double-bogey at the opening hole and reeled off nine successive pars after the turn to post a four-under total of 206 on a fast-running layout.
World number one Woods, four off the pace overnight, played conservative golf to return a 69 in pursuit of his third successive victory at one of his favourite venues.
The 31-year-old American, who has never finished worse than tied for fourth in eight appearances at the event, will start Sunday's final round alone in second place.
Fellow American Kenny Perry (71) was a further two strokes back in third at one under.
'I just tried to stay as patient as possible,' Woods told reporters after a round featuring three birdies and two bogeys.
'I played ultra-conservative out there today, dumped the ball in the centre of the green and if I happened to make a putt; that was great. You can make double out there in a heartbeat.'
Sabbatini, bidding for his fifth PGA Tour title, produced a roller-coaster outward nine on a brutal, fast-running course with very little margin for error.
The 31-year-old South African double-bogeyed the opening hole after driving into a fairway bunker and hitting a tree with his second shot.
After partially recovering with a birdie at the par-five second, he dropped another shot at the treacherous par-four fourth where he narrowly missed a seven-footer.
Sabbatini, winner of this year's Colonial tournament, got back to five under after hitting a superb tee shot to four feet at the par-three fifth before also bogeying the ninth.
He held his nerve as the breeze began to pick up in the afternoon, and narrowly missed a birdie putt from 12 feet at the last to regain a two-shot cushion.
With thunderstorms forecast for Sunday's final round, tee off times have been brought forward and the field has been split into a two-tee start.
Padraig Harrington finished on three-over, with Paul McGinley and Darren Clarke down the field on nine-over and 12-over respectively. Two consecutive three-putts cost Harrington early momentum.
He said: 'The first five holes I had good chances on all of them but missed a couple of putts. Everything is looking good and then I lost the focus.
'I had a careless three-putt on the sixth and made a double-bogey and three-putted the next so that kind of put me on the back foot for the rest of the day.
'After a couple of three-putts in a row, I did not putt anywhere near as well as I had been putting.'
