Thomas Pieters will share the lead with Zach Johnson heading into the final round of the WGC-Bridgestone Invitational after firing a topsy-turvy 66 on day three at Firestone Country Club.
The big-hitting Belgian held a three-shot lead at one point and while he could not maintain his momentum on the back nine, a closing birdie put him back into the final group on Sunday.
Johnson recorded a 65 to join him at nine under, a shot clear of Australian Scott Hend - who signed for a brilliant 63 - and two ahead of World Number Three Hideki Matsuyama.
Northern Ireland's Rory McIlroy, Canadian Adam Hadwin and American Charley Hoffman were then at six under.
Pieters was playing in just his sixth World Golf Championships event but has never finished lower than 30th with a best result of tied for fifth at the WGC-Mexico Championship earlier this year.
"The first eight holes I was in the fairway, hit good shots, made putts and the last 11 was a struggle," he said. "I just was out of position every hole. Tomorrow I've just got to figure out a way to hit fairways, that's it. My bad golf is getting better. That's always good, that's why you practise.
"I struck the ball really well with the irons, ball striking's been really good. Off the tee not so good but I think I'm missing it in the spots I can miss it in. All in all, not too bad.
"You just want to be in contention on Sunday afternoon, that's it."
Hend had birdies on the first, fifth, sixth and eighth to go with a bogey on the seventh to turn in 32. He added further gains on the tenth and 14th and a brilliant tee-shot on the par three 15th moved him two off the lead.
Another birdie on the 18th gave him the lowest round of the week by two shots and the clubhouse lead but he was still two behind Pieters who was looking unstoppable.
He put his approach to the first to eight feet to get to six under and then played a remarkable second after a poor tee-shot on the second and got down in two for a birdie.
A perfect tee-shot on the next then allowed Pieters to put an approach to tap-in range and he led by two.
Another excellent shot from the peg, this time to six feet on the par three fifth, extended the lead to three and while the chasing pack continued to jostle behind him, a wonderful second into the eighth left Pieters with nine feet to get to ten under.
He was staring a double-bogey in the face after a poor tee-shot and chip on the ninth but he holed a clutch putt and held a two-shot advantage at the turn and got back to double figures as he bounced back on the next.
Back-to-back bogeys on the 13th and 14th saw the 25 year old fall into a share of the lead but he hit a brilliant approach into the par five 16th and led again before dropping another shot on the 17th.
Johnson - a two-time Major Championship winner - had seven birdies and three bogeys in his first 17 holes and when he rolled in another gain on the last, he held the lead.
It looked like he would be the only man at nine under heading into the final round when Pieters found the rough with his drive up the last but an excellent second and a stunning 33-footer handed him a closing birdie.
Matsuyama had five birdies and two bogeys in his 67, while Hoffman and Hadwin signed for the same score while making six birdies in their rounds.
McIlroy was level par after ten holes but birdied the 11th before chipping in on the 12th en route to a 68.
Russell Knox also recorded a 68 to sit at five under, a shot clear of Paul Casey.