Adam Scott held a slender advantage at the top of the leaderboard as the World Golf Championships-Bridgestone Invitational moved towards a dramatic conclusion at Firestone Country Club in Akron, Ohio.
Overnight leader Scott completed his front nine in 34 strokes, having combined eight pars with a birdie at the par five second.
That lifted him to 13 under for the tournament, yet a host of players remained in close contention behind the Australian.
Japanese teen sensation Ryo Ishikawa and unheralded American Keegan Bradley led the chasing pack and were just one shot back, with the former having shared the lead for much of the front nine.
Ishikawa, who doesn’t turn 20 until next month, picked up shots on the second, third and sixth holes, but bogeys at four and eight, where he failed to get up and down from beside the green, stunted his progress.
Bradley, meanwhile, bogeyed the first hole, but recovered superbly with birdies at two, six and eight.
World Number One Luke Donald was a shot further back, having birdied the first and 10th either side of eight successive pars.
Rickie Fowler was two under for his round and alongside Donald and Jason Day on 11 under, yet the young American could have been in an even stronger position were it not for three successive missed birdie opportunities from the sixth.
Lee Westwood, Donald’s nearest rival in the Official Golf World Rankings, was enjoying a sensational day and had climbed into a tie for seventh on nine under courtesy of five birdies.
Westwood had just two holes to play, so his chances of victory were remote. However, the Englishman could take great heart from his final-round performance ahead of next week’s US PGA Championship.
Also on nine under were Scotland’s Martin Laird and US Open Champion Rory McIlroy, who followed a bogey at the opening hole with birdies on the second, fourth and eighth.
Former World Number One Tiger Woods could only muster a 70 and ended the week one over.
After his round, Woods said: “I had it in spurts this week. I hit it really well, and then I'd lose it and get it back. Today was a good example of that.”
Woods also expressed his admiration for Ishikawa’s efforts, adding: “Give this kid another decade, he is going to be unreal.
“He makes a ton of putts, he usually drives it on a string, and he's learning how to flight his golf ball down better. As I said, give him a decade, and he's going to do great things.”