Kevin Chappell is the man to beat at the halfway stage of the Deutsche Bank Championship after taking a one-stroke lead in the second round.
Chappell was almost flawless at TPC Boston on Saturday, carding a seven-under-par 64 to climb atop the leaderboard.
The American - 13th in the FedEx Cup rankings before this week's second PGA Tour play-off tournament - holed six birdies and an eagle, with his only blemish coming at the 13th, a bogey.
Chappell is a shot ahead of Paul Casey and Jimmy Walker at 11 under through 36 holes.
Englishman Casey posted a bogey-free second-round 66 to be within touching distance of Chappell, while U.S. Open champion Walker - a month on from his maiden major title - rocketed into contention with a seven-under-par 64.
A shot behind is Brian Harman - who was 65 through 18 holes, with Smylie Kaufman and Dustin Johnson tied for fifth at eighth under following rounds of 66.
Ryan Moore went from top of the pack to a share of seventh after beginning his second-round 70 with three bogeys from five holes.
Brian Stuard (69), Daniel Berger (68), Gary Woodland (66), Justin Rose (67) and FedEx Cup leader Patrick Reed (67) - who won last week's Barclays - are also seven under.
This set up a second consecutive birdie for Jordan Spieth. https://t.co/vYkdIbIpso-- PGA TOUR (@PGATOUR) September 3, 2016
Reigning FedEx Cup champion Jordan Spieth shot another 68 to be five shots off the pace, two ahead of Rory McIlroy, who produced an improved putting performance for a four-under 67.
World number one Jason Day, meanwhile, endured a difficult round after quadruple-bogeying the fifth hole as he stuttered to an even-par 71, finishing just a shot above the cut line.