ATLANTA (AP) -- Dustin Johnson made one mistake that suddenly put some intrigue into the final day of the PGA Tour season - the Tour Championship and the FedEx Cup.
Johnson clipped a tree trying to get out of the rough on the 17th hole and made double bogey, and only a birdie on the final hole at East Lake on Saturday allowed him to shoot a 1-under 69 and regain a share of the lead with Kevin Chappell.
Chappell went from a four-shot deficit on the front nine to a one-shot lead when he made a 10-foot birdie putt on the 17th and Johnson made his double bogey. Chappell, still looking for his first PGA Tour victory, shot a 68.
They were at 8-under 202.
Rory McIlroy and Ryan Moore each had a 66 and have different prizes at stake Sunday. They were two shots behind, still very much in the game after wondering most of the steamy afternoon if Johnson was going to give anyone a chance.
Johnson still has control of the $10 million bonus for winning the FedEx Cup. He only has to win or finish second alone in the Tour Championship to win the cup. McIlroy, five shots behind at the start of the third round, would have to win the Tour Championship and have Johnson finish in a two-way tie for second.
On this course, and after the way Saturday finished, it no longer looks like such a stretch.
''I just need to try and win this golf tournament, and whatever happens after that, happens,'' McIlroy said. ''It would just be great to try to win the Tour Championship, and if the chips fall my way, then so be it.''
Moore went out in 31 until he was slowed by a pair of bogeys, though very much in the mix just two shots out of the lead. The mystery is whether anything he does on Sunday - even if that means a victory - is enough for Davis Love III to use his last captain's pick on Moore for the Ryder Cup.
''I came here this week to win a golf tournament, and I'm 100 percent focused on that,'' Moore said, adding that the Ryder Cup is ''completely out of my control.''
And that's how the last day is shaping up for everyone - post a score and see where it leads.
Hideki Matsuyama of Japan had a 68 and was three shots behind, while Jason Dufner had a 66 was four back.
Johnson, for a moment, looked as though he might take all the drama out of the season-ender when he made a 15-foot par putt early in his round and then ran off three straight birdies on the front nine to go four shots clear.
The putter cooled off, however, and Chappell stayed in range. Chappell chipped in on No. 12 to match birdies and stay three shots behind, and then he quickly closed the gap when Johnson made back-to-back bogeys with a three-putt from 70 feet and a drive into the dense rough that was too thick even for his strength to get near the green. But he answered with a 4-iron over the water to a peninsula green on the par-3 15th to 15 feet for birdie.
The 17th hole changed everything.
Johnson caught a reasonable lie in the right rough, but instead of playing it low under a pine branch to the front bunker for a simple chance at making par, he tried to play a fade from a flyer lie, caught a branch and wound up in deep rough. He put his next shot in the bunker, chipped to 6 feet and missed.
He still was tied for the lead after his up-and-down from the bunker on the par-5 18th for a birdie. He still had his eighth consecutive round in the 60s.
''I like my position,'' Johnson said. ''I feel like I'm playing really well. I need to go out tomorrow and do the same thing I did today, and hopefully try to finish off a little better.''
Chappell made a David versus Goliath comparison Friday, and it felt like that at times with how far Johnson hits it and the support he had from a Southern crowd. But the California kid never flinched even when he fell behind early, and he has gone 54 holes at East Lake with only one bogey.
Plus, he gets one more crack at the hottest player in golf.
''I got nothing to lose,'' Chappell said. ''I'm going to go out there and give it all I've got, and Dustin is going to play great golf. He's been in this situation a lot this year, and it will come down to one or two shots.''