Jason Day displayed shades of the form that saw him win the US PGA Championship to claim a share of the lead at The Barclays on Saturday.
The world number three shot an impressive seven-under 63 to catapult himself into the lead alongside South Korea's Sang-moon Bae heading into the final round at Plainfield Country Club.
Day carded six birdies, plus an eagle on the par-five 16th hole.
His lone bogey came on the par-four 17th, although he regained that stroke, with a birdie on the 18th.
"I didn't expect to come out and shoot 63 today," Day said on CBS.
"I knew there were some pins we could attack, but this is still a good confidence-booster heading into the final round."
Playing alongside Day was Bae, who also shot a 63.
The South Korean made a number of clutch putts throughout his round, matching Day shot for shot.
Overnight leader Bubba Watson (67) finished the third round at 10-under overall - one behind Day and Bae.
Watson was solid if not unspectacular and he will have to be better at finishing off his birdie opportunities on Sunday, or Day will run away with another event.
Ryan Palmer (65), Zach Johnson and Sweden's Henrik Stenson (both 67) share fourth position at nine under.
Johnson - the 2015 Open Championship winner - stalled on the back nine after starting the day four under through 11 holes.
The 39-year-old could only manage six pars and a bogey on the 18th on his run home.
Mexico's Carlos Ortiz shot the round of the day - an eight-under 62 with five birdies on the back nine - to jump 43 spots up the leaderboard into a share of seventh at seven-under overall.