Open champion Jordan Spieth took a massive step towards his fourth win of the season with a brilliant third round of 64 to take command of the Northern Trust Open.
Spieth began the day in a four-way tie for the lead and recovered from a bogey on the first with birdies on the third, fifth, seventh and eighth before surprisingly three-putting the ninth from just eight feet.
The three-time major winner bounced back with his fifth birdie of the day on the 10th and carded three more in succession from the 14th to finish 12 under par, three shots ahead of world number one Dustin Johnson.
Spieth had been four clear until Johnson birdied the 18th to complete a 67 and move two ahead of Paul Casey, Jon Rahm, Patrick Reed and Matt Kuchar.
Spieth, who has won each of the five times he has enjoyed a lead of two shots or more after 54 holes on the PGA Tour, admitted a "heated putter" had been crucial to his success.
"I've been striking the ball well this year," the 24-year-old told Sky Sports. "Today was about the most committed I've been finishing a round - Michael (Greller, his caddie) said ever - and I agreed with him.
"(We) committed to targets that were away from holes, knowing I'm in the lead and knowing the putter is getting hotter each putt I hit. That last six-hole stretch I played beautiful golf."
Casey put his 66 down to a simple tip from coach Peter Kostis, the world number 17 finishing strongly with three birdies in his last six holes.
"I saw Peter on the range this morning and he said I was standing too far away from the ball," Casey said. "I moved closer to the ball and the ball-striking was wonderful today.
"Peter always tells me 90-something per cent of the time the reason for a bad shot is something you do before you even hit the ball, whether that's set-up, posture, grip, bad decision... this week has been an example of that."
Rory McIlroy carded four birdies and three bogeys in a 69 to get back to level par for the tournament.
The top 100 in the FedEx Cup standings after this week's event will advance to the Dell Technologies Championship at TPC Boston, where Rory McIlroy is the defending champion.
American Lucas Glover suffered a strained patella tendon as his right foot slipped on his second shot to the 18th, but the former US Open champion said he intended to play Sunday's final round. Glover is two over par after a 72.