Jon Rahm achieved a 36-hole first when taking the lead of the Northern Trust at the halfway stage.
Rahm, the world number one, was bogey-free through 36 holes for the first time in his career after adding a second-round 67 to his opening 63 at Liberty National in New Jersey.
Rory McIlroy sank a four-foot putt at the last to make the cut on one under, while Shane Lowry -4 and Seamus Power -5 are both in good shape heading into the weekend.
"It's nice to be bogey-free but it's not like it's goal number one," Rahm told the Golf Channel after taking a one-shot advantage over Tony Finau in the opening FedEx Cup play-off event.
"The goal is to win a tournament, to put yourself in the best position.
"If I had to choose I'd rather be leading than bogey-free."
Asked what pleased him most about his play, Rahm replied: "The way I've kept my composure. Believe it or not, I've hit my share of bad shots and leave myself putts for par.
"But much like yesterday I was able to save a couple of good ones.
"Coming to the weekend I'm definitely going to have to clean a couple of those mistakes up."
Finau's 64 placed him one back from Rahm on 11 under and one ahead of Justin Thomas.
American Thomas had shared the overnight lead with Rahm, but four bogeys on his front nine dropped him back down the field.
Thomas, however, rallied with three birdies and an eagle in four of his last five holes.
Keith Mitchell and Olympic champion Xander Schauffele - whose 62 tied the course record, a score later equalled by Jordan Spieth - joined Thomas in a tie for third with four players one shot further back.
Lee Westwood was five shots adrift of Rahm after a 65 featuring seven birdies, while fellow Englishmen Ian Poulter and Paul Casey also made the weekend.