Paul Casey moved clear at the Tour Championship, taking a two-shot lead after the third round in the race for the FedEx Cup.
Englishman Casey carded a five-under-par 65 to surge ahead of the 30-man field at East Lake Golf Club on Saturday.
Locked in a three-way tie alongside Justin Thomas and Webb Simpson when he teed off on the weekend, Casey quickly broke away from the pack with three birdies and an eagle in his first seven holes.
Casey then made a monster putt on the par-four 17th hole to cement his status as tournament leader at 12 under heading into the final round.
With one solitary PGA Tour title to his name, Casey is poised to win the FedEx Cup as he tops the play-off rankings ahead of U.S. Open champion Thomas and former number one Jordan Spieth.
Kevin Kisner, who shot a six-under-par 64 and breakout star Xander Schauffele (65) are tied for second at 10 under.
Both started the week outside the top 15 in the standings, so they need an abundance of help to win the FedEx Cup, even with a victory on Sunday.
Dell Technologies Championship winner Thomas two-putted for birdie on the par-five 18th hole to move into a tie for fourth at seven under.
The birdie also moved him ahead of fellow American Spieth for second in the FedEx Cup standings entering the final round.
Brooks Koepka (68), who bogeyed three out of his last four holes, and Patrick Reed (69) are level with Thomas, while Jason Day (68) is a shot further back.
Spieth and world number one Dustin Johnson fired matching third-round 69s to be four under through 54 holes.
Three-time major champion Spieth does not necessarily need to win the Tour Championship to claim the FedEx Cup, but he needs to either climb up the leaderboard on Sunday, or have someone other than Casey or Thomas win the tournament.
Masters winner Sergio Garcia (68) is three under, while BMW Championship victor Marc Leishman is 13 strokes off the lead following his 69.
With defending champion Rory McIlroy out of the field this week, East Lake will crown a new FedEx Cup champion.