The American golfer Jordan Spieth fired two late birdies to overtake Sweden's Henrik Stenson and grab a one-stroke lead after the third round of the PGA Tour's season-ending Tour Championship in Atlanta.
Spieth carded a two under par 68 that lifted him to eight under for the tournament.
New Zealand's Danny Lee carded a one under par 69 to move to even par for the tournament, eight shots behind Speith in a tie for 10th.
Spieth poured in a 20-foot birdie putt at the last to cap off a fine day on a layout left drenched after a second successive day of rain.
Swede Stenson began the drizzly day with a three-shot lead over Spieth, but his mastery of the venerable course waned in the soggy conditions as he posted four bogeys and two birdies for 72 and a 203 aggregate.
Tied for third place, four strokes off the pace at 206, were Rickie Fowler, who best solved the East Lake puzzle with a three-under 67, and Englishman Paul Casey, who shot 71.
Four-times major winner Rory McIlroy (70) and British Open champion Zach Johnson (71) were another shot behind at three under par.
Besides the more than $2 million first prize, a victory for any of Spieth, Stenson or Fowler would also clinch them the $13 million FedExCup playoffs bonus.
Players struggled through a second successive soggy day at East Lake, and although they were allowed to lift, clean and place balls on the saturated fairways, the 7,300 yard layout played longer and thoroughly tested the elite field of 28.