FARMINGDALE, N.Y. -- Defending champion and first-round leader Brooks Koepka kept his momentum going through Round 2 of the 101st PGA Championship on Friday, firing a 5-under-par 65 at Bethpage Black in Farmingdale to build a seven-stroke lead over Jordan Spieth and Australia's Adam Scott.
Koepka's playing partner, Tiger Woods, missed the cut by a shot after shooting 73 on Friday to finish at 5 over for the tournament.
Koepka opened with three birdies over his first four holes, experienced a few hiccups on the back nine with bogeys at Nos. 10 and 17, but carded four more birdies -- including one on No. 18 -- to finish at 12-under 128 for the lowest 36-hole score in major championship history.
"Today was a battle," Koepka told TNT after his round. "I did not hit it very well today. I was fighting just a block (shot), but I was able to find a couple fairways, thankfully, and when I did miss a fairway, it was in a great lie. ... I'm still putting really well. I hit my lines and feel very comfortable over these putts, which is big."
Chasing history and his elusive major form at the same time, Spieth shot 66 on Friday morning to charge into a tie for second at 5 under.
Spieth, No. 39 in the world rankings, is attempting to become just the sixth player to win the career Grand Slam, but he entered the week without a top-20 finish so far this season, and he hasn't posted a top-10 finish since last year's Open Championship. And while he's aware of his so-called slump, Spieth has insisted all week that his game is coming together.
"I haven't been in contention on a Sunday since The Open last year, and if I'm able to put some good work in tomorrow, then ... I will be in contention on Sunday," said Spieth, who is third on the PGA Tour in second-round scoring this season.
"At that point, it will be just more of trying to win a golf tournament. It won't matter to me what tournament it is. I'll be pleased to be in contention, knowing that the work I put in from being pretty far off has really come back nicely on a very difficult golf course."
Scott rebounded from an opening-round 71 with the low round of the day on Friday, posting a 64 to reach 5 under for the tournament. He carded four birdies on the front nine and three more on the back -- with his lone bogey at No. 17 -- to tie his career low round in a major championship.
"Everything was pretty solid today," said 38-year-old Scott, who finished third at the 2018 PGA Championship. "It was nice to kinda keep the momentum going with the saves and post a number, but, you know, I'm going to have to post two more pretty good ones by the looks of things at this stage."
Rounding out the top spots on the leaderboard were Englishman Matt Wallace (67) and a foursome of Americans, Daniel Berger (66), world No. 1 Dustin Johnson (67), Kelly Kraft (65) and Luke List (68). They all share fourth place at 4 under.
Starting on the back nine, Johnson bogeyed No. 10 before going on a tear that included five birdies over a seven-hole stretch to get to 5 under for the day. His charged stalled with a couple of short missed putts, as Johnson was 1 over par across his final 10 holes.
"I felt like I did a really good job today," Johnson, who has hit 30 of 36 greens this week, told TNT. "I hit the ball really, really well ... gave myself a lot of looks at birdie. Made some nice putts but missed quite a few short ones. The greens are really tricky to read ... lot of subtle breaks.
"I'm pleased with the score again and pleased with how I played."
Kraft, the last player to be added to the field when Justin Thomas withdrew, took advantage of the opportunity and carded his lowest round in a major to date. He had one bogey and six birdies on the day.
"I feel like I may need to send Justin a bottle of wine or something, but it's been good," said Kraft, 30, who has yet to win on the PGa Tour.
"I've been playing really well. I've been hitting a lot of fairways. The driver is going where I'm looking, and the game plan is just to get as many birdie looks as we can and see what happens, and I rolled a few of them in today."
Along with four-time tournament winner Woods, several former champions missed the cut, including Germany's Martin Kaymer (2010; 5-over 148), Jason Dufner (2013; 8 over) and Ireland's Padraig Harrington (2008; 12 over). John Daly, the 1991 champion who was allowed to use a cart this week, missed the cut after shooting a 6-over 76 on Friday to finish 11 over for the tournament.
World No. 11 Jon Rahm of Spain missed by one after shooting 70-75, as did countryman Sergio Garcia, who shot 74-71.