Sangmoon Bae and Jason Day are tied for the lead at The Barclays after firing rounds of 63 to move up seven places on the leaderboard.
US PGA winner Day's round was highlighted by an eagle on the par-five 16th, while Bae overcame two bogeys as he piled up the birdies.
Day will go into Sunday hoping to join Jordan Spieth - who missed the cut here on Friday - as the only two men to win four times this season, while he could also claim back-to-back victories and a third in four outings.
Overnight leader Bubba Watson slipped one shot back as he went round in a solid if unspectacular 67, with a bogey on the seventh proving costly.
Open champion Zach Johnson and Henrik Stenson also signed for 67s, slipping down to a share of fourth alongside Ryan Palmer.
Tony Finau, who had started one day off the lead, had a poor afternoon with three bogeys in a round of 71 which sent him down to a tie for 14th.
The best round of the day belonged to Carlos Ortiz, who went around in 62 - 11 better than his opening round effort - to move up 43 places to a share of seventh, four shots off the lead.
Ortiz had eight bogeys on a blemish-free day.
Justin Rose was also a big mover on the leaderboard, matching Bae and Day with a 63 which lifted him up 50 places to a share of 14th as he continues his recovery from an opening day 77.
Source: PA
