Henrik Stenson carded a 4-under 66 on Friday to push his lead to four strokes after two rounds of The Tour Championship.
Stenson ended 36 holes at East Lake at 10-under-par 130. The Swede collected his third PGA Tour win three weeks ago at the Deutsche Bank Championship.
This is the finale of the FedExCup Playoffs and the winner of the Tour Championship has the chance to win both titles at the same time. Stenson is second to Tiger Woods on the points list and would win both crowns with a victory this week.
Masters winner Adam Scott managed a 1-under 69 to remain alone in second place at minus-6.
Jordan Spieth, who started the season with no status on tour, shot 3-under 67 to move into third place at 5-under 135.
U.S. Open champion Justin Rose (68), Dustin Johnson (68) and Billy Horschel (70) are tied for fourth at minus-4. Five Americans, including Steve Stricker and Zach Johnson, share seventh place at 3-under 137.
Stenson led Scott by one after the opening round, but four holes into the second round that lead increased to five. Stenson birdied the first and second from a similar distance to move to minus-8.
Scott tripped to a bogey at the first and found himself four back after Stenson's birdie at two. Scott got one shot back with a birdie on the third, but there was a two-stroke swing at the fourth.
Stenson, who is playing in his first Tour Championship, poured in a 27-foot birdie putt, while Scott tripped to another bogey to fall five back.
The duo matched four straight pars from the fifth. They both birdied the par-5 ninth, but Stenson failed to save par from a bunker on No. 10 to slip to minus-9.
Scott ran off six straight pars from the 10th, while Stenson parred five in a row from the 11th. Stenson rolled in a 22-footer for birdie at the 16th. Scott answered from eight feet out. The duo parred the final two holes.
"I still hit a lot of nice iron shots and got it really close on a few occasions. I was quick out of the blocks today as well, 3-under through four, and nice birdie on nine," Stenson said. "I just didn't capitalize on chances on 13 and 14. Then I hit another great putt on 15 that somehow managed to miss, but I got it back on 16 and finished with two nice pars."
Prior to the round, Stenson caved in the face of his fairway wood and was unable to replace it before the round started, so he played the round with 13 clubs, one less than the maximum allowed.
"I caved in the face on the top groove, so we put that one in the locker," Stenson said. "We'll try to pull the shaft out and see if we can find a head that would do the job for the last two rounds, otherwise I'll keep on playing with 13."
Scott, the 2006 winner, collected his second win of the season a month ago at The Barclays, the first FedExCup Playoff event.
"It was a little scrappy out there today, but I didn't think I was in that much trouble at any point. It was good to have a couple of saves on the back nine," Scott stated. "I couldn't get any of the putts to go."
World No. 1 and two-time winner Woods had five birdies through 13 holes and was about to move into the top 10, but he dropped six shots in a 4-hole span en route to a 1-over 71. That left Woods tied for 26th at 4-over 144.
Woods' rough stretch included a bogey, a double bogey and a triple bogey.
"I put everything I had into that start and didn't have much at the end. Just ran out of gas," Woods admitted. "My legs were just tired. I didn't rotate through the ball on 17, and I turned it over. Same thing I did over on what was it, 14? Same shot. It's been just a long, long grind. We play a lot of golf from the British Open on."
Defending champion Brandt Snedeker struggled to a 5-over 75. He fell into a tie with Woods and Jason Dufner (70) at plus-4. Since the FedExCup playoffs started, Snedeker is the first Tour Championship winner and FedExCup champ to qualify for the following year's Tour Championship.
NOTES: Stenson owns a piece of the 36-hole lead for the third time in his PGA Tour career. In the previous two occasions, Stenson failed to finish inside the top 10 ... Tee times were moved up on Saturday with inclement weather in the forecast.