England's Luke Donald is two shots behind leader Adam Scott after firing a two-under-par 68 in the second round of the Tour Championship in Atlanta.
Australian Scott is one shot clear of South Korean KJ Choi after two closing birdies saw him hit a second-round 65.
Scott, who leads the projected points race, was two over par after six holes before a run of four straight birdies.
Donald is the only one of the top five in contention for the victory, which would guarantee the FedEx Cup.
American Webb Simpson, the points leader entering the event, is seven strokes behind while his compatriot Dustin Johnson, who was second in the standings, is a further four shots back.
England's Justin Rose is 12 shots behind after shooting a five-over-par 75 in a second round which included two double bogeys.
Donald started his second round with a birdie but took a bogey on the next hole.
The world number one also followed a birdie with a bogey on the seventh and eighth but began the back nine with a birdie and added another at 15 to move into a share of third with Australian Jason Day.
Overnight leader and US PGA champion Keegan Bradley fell to three shots behind the leaders after a one-over-par 71.
As it stands, Scott leads the projected points race from Simpson with Donald in third and Choi in sixth.
At one stage there was a six-way tie for the lead at five-under between Scott, Day, Choi and Americans Bradley, Bubba Watson and Hunter Mahan with all six topping the play-off points chase.
Donald is also second on the PGA Tour money list for 2011 and top of the European Tour equivalent, the Race to Dubai, and is bidding to become the first player to win both lists in the same season.