Jordan Spieth had a two-round total of 135, one shot ahead of US compatriots Dustin Johnson and Daniel Berger.
BETHPAGE - Jordan Spieth, trying to complete a career Grand Slam despite a season of struggles, fired a four-under par 66 to take the early clubhouse lead in Friday's second round of the PGA Championship on five-under par.
Defending champion Brooks Koepka, who had yet to tee off, still topped the leaderboard on seven under.
Spieth, without a top-20 result this year or a victory since the 2017 British Open, had a two-round total of 135, one shot ahead of US compatriots Dustin Johnson and Daniel Berger.
"Confidence has been there," Spieth said. "I figured if I stayed out of my own way, stick to one thought, (my game) was in good enough shape to contend."
Spieth could become only the sixth golfer to win each of the four majors at least once, joining Tiger Woods, Jack Nicklaus, Gary Player, Gene Sarazen and Ben Hogan. But he doesn't expect that to create extra pressure.
"I haven't been in contention since the (British) Open last year. If I put in some good work tomorrow I'll be in contention on Sunday," Spieth said.
"At that point, it will be about winning the golf tournament. I imagine that will take pretty much most of my thoughts. But we'll see."
Spieth's charge came before Koepka teed off. He is in a group with Woods and British Open champion Francesco Molinari, who were battling to make the cut after opening 72s.
The layout at Bethpage Black teased some hopefuls and tortured others but allowed no one to match Koepka's seven-under par 63 course record from Thursday.
"You don't expect Brooks to fall at all," Spieth said. "I felt like I had to be within six or seven going into the weekend."
Back-nine starter Spieth, the 2015 Masters and US Open champion, sank a 15-foot birdie putt at 11 but made bogeys at 15 and 16 after finding rough and deep weeds off the tee.
Spieth, ranked 39th, answered with a birdie putt at 17, sank another from 20 feet at the first, added another at four and made back-to-back birdies at seven and eight to seize second.
"The front nine is a little more gettable," Spieth said. "I need to hit more fairways. Scrambled really well. Ball just needs to find as many fairways as DJ or Brooks."