There was everything to play for heading into the final round of the AT&T National, with American trio James Driscoll, Bill Haas and Roberto Castro, and Argentina's Andres Romero tied on seven under at the top of the leaderboard at Congressional.
Romero had held the upper hand midway through his round, but a double-bogey at the par-four 11th was followed by another dropped shot on 12.
He recovered to par the remaining six holes and signed for a one-under-par 70.
Haas also had trouble at the 11th, posting a triple-bogey seven, but swiftly recovered the three shots with birdies in three of the next four holes en route to a 68.
"It's not perfect golf, but you don't really have to play perfect golf sometimes" - James Driscoll
The American, who has not won on the PGA Tour since February last year, seemed to acknowledge his putting was key to moving into a share of the lead.
"It could have been a six, seven, eight under day," Haas said to www.pgatour.com. "But it also could have been a four, five, six over day if I hadn't putted well."
Driscoll also carded a 68 and is now the only player in the field to shoot three sub-70 scores this week.
"It's not perfect golf, but you don't really have to play perfect golf sometimes," he said.
"If you're just patient and putt well and have a good short game, it can go a long way, and that's kind of what I'm doing this week."
Birdies on 16 and 17 helped Castro (71) finish strongly - having been three over for the round through three holes - although it was the American's outrageous 80-foot chip-in for par on the 18th which ensured he remained among the names at the top of the leaderboard.
"It (the round) was a rollercoaster but I settled down in the last seven holes," he said.
"On 18, I hit a good pitch and bogey would have been good but a par was just a bonus."
Jason Kokrak was a stroke back in fifth place after a 70, with compatriot Tom Gillis and South Korea's Charlie Wi a further shot adrift in a tie for sixth after sparkling rounds of 66 and 65, respectively.
It was a disappointing day for rising star Jordan Spieth, who was tied for the overnight lead alongside Castro but dropped back into a share for eighth after a three over par 74 today.