Patrick Reed shot a four-under-par 67 to take a one-stroke lead into the final round of the Northern Trust in New Jersey.
The 2018 Masters champion shone with five birdies in his third round at Liberty National but he was being hunted by a host of big names in the first FedEx Cup play-off event.
Reed, on 14 under, led by one from American-born Mexican Abraham Ancer, who shot 68, but Justin Rose, Danny Willett and Rory McIlroy were among a strong chasing pack.
"It feels great," said Reed on Sky Sports. "I have been hitting the ball well and feel like I've had control of the golf ball for a month and a half now. To finally see it pay off and be in contention going into Sunday is all I could ask for."
Brandt Snedeker was one of the biggest movers of the day, climbing into a tie for third with Jon Rahm after holing five birdies and two eagles in a brilliant 63.
Yorkshire's Willett also made good ground, recording a five-under-par 66 to move into joint fifth on 11 under alongside Rose and Harold Varner. It could have been even better for Willett, who had five birdies and an eagle on his card, but for a bogey on the 18th.
Rose shot a 69 with a lot of good work, including four birdies and an eagle, undone by four dropped shots.
Rory McIlroy also had four bogeys in a 70 and was one stroke back on 10 under.
Second round leader Dustin Johnson failed to spark, shooting 74 to slip to nine under while FedEx Cup leader Brooks Koepka was even further back on five under after a 69.
Ian Poulter climbed the leaderboard with three birdies on the front nine but but gave all those shots back after the turn to end where he started on eight under, along with Jordan Spieth.
Reed takes one shot lead into final round at Northern Trust
