Scott birdied the 14th and eagled No. 15 en route to a 3-under 67 in round three. That moved him to 7-under-par 203, three clear of second-round leader Joe Durant and Vijay Singh. Scott is the only player with three rounds in the 60s this week.
'It's a great position to be in,' Scott said of holding the lead. 'I'm going to need to play another really great round of golf tomorrow.
'I think you can see all the great players making a bit of a move today and creeping up the leaderboard, so I've got a lot of world class players right behind me. I'm sure one of them will get out there and make some birdies and try and chase. I've got to keep moving in the right direction.'
Durant struggled to a 1-over 36 on the back nine to fall to 4-under-par 206. He managed an even-par 70 in round three. Vijay Singh, the 2002 winner here, was 5 under on the back nine as he posted 5-under 65, the low round of the week. He shares second with Durant at minus-4.
A pair of former U.S. Open winners -- Retief Goosen (68) and Jim Furyk (67) -- share fourth place at minus-3 at East Lake Golf Club.
Scott and Durant battled throughout the round. Scott gained the upper hand early with a 2-foot birdie putt on the first. Durant tripped to a bogey on three, when he could not save par from a greenside bunker. That dropped him to minus-3, two behind Scott.
Durant made his charge late on the opening nine. As Scott was in the midst of running off 11 consecutive pars, Durant erased the two-shot deficit.
The 42-year-old Durant kicked in a 3-footer for birdie at the eighth and made it two straight as his 11-foot birdie putt on nine found the bottom of the cup.
Durant briefly took the lead by himself with a 4-foot birdie putt on the 12th. Both Scott and Durant bogeyed the par-4 13th.
Scott regained a share of the lead when he made a 4-footer for birdie on 14. At the par-5 15th, the Australian sank a 2-foot eagle putt to jump to minus-7. That eagle was just the second of the week for the entire field. Luke Donald posted the other eagle on the 15th on Friday.
'That was important for me,' said Scott of the turnaround on 14 and 15. 'It really changed the whole tournament from my end of things. Birdieing 14 was great, but making a three at 15 really pulled me back out in front, in a position I like to be in.'
Durant was only one back as he made birdie from 12 feet on No. 15. However, trouble loomed for the four-time winner on the PGA TOUR. Durant missed the green left on 16 and could not save par. Then he three-putted for bogey on 17 to fall three back.
'I didn't play particularly well today. My swing didn't feel very good,' Durant admitted. 'I was going over the top of a lot of my shots. You need to drive it well here, and I didn't drive it with any kind of conviction today, really. I was more or less just guiding it around.'
Scott two-putted for par on 16 and 17, then got up and down for par at the last to take a three-shot cushion into the final round.
Singh was even-par over the first nine holes with a birdie and a bogey. The Fijian converted a birdie putt on No. 10 to move to even-par for the tournament. Singh ran off four straight birdies from the 12th to jump to minus-4 and into a share of second.
'I played pretty decent,' stated Singh. 'I was just hanging around on the front nine and got it going on the back nine. I hit some really good shots and made some nice putts.'
Tom Pernice, Jr. carded a 3-under 67 Saturday. He was joined in sixth place at 2-under-par 208 by Trevor Immelman, who carded a 69.
Ernie Els used a 4-under 66 to move into a share of eighth at minus-1. He stands alongside Donald, who posted 69 in round three. Lucas Glover is alone in 10th at even-par 210 after shooting 66 in the third round.