Brooks Koepka continues to make history at halfway stage of US PGA Championship

Koepka also finished a staggering 17 shots ahead of playing partner and Masters champion Tiger Woods, who missed the cut after adding a 73 to his opening 72.

"I've enjoyed being the Masters champion again and the PGA was a quick turnaround and unfortunately I just didn't play well," said Woods, who had been unable to practice on Wednesday due to illness.

"I didn't do all the little things I need to do correctly to post good scores and put myself in position to shoot good scores."

Woods had been the only player to finish under par when he won the 2002 US Open at Bethpage, with Lucas Glover winning on four under when the tournament returned to the same venue seven years later.

Koepka, who is seeking a fourth major victory in his last eight starts, said: "Today was a battle. I did not hit it very well today, I was fighting a bit of a block. I was able to find a couple of fairways and when I did miss I was in a great lie. I'm still putting really well which is big.

"I feel good, especially the way I battled today, to not have it and get that score I am very proud of myself. I fought hard, I feel great and just need to continue on the weekend."

Scott had the chance to equal or even better Branden Grace's all-time major record of 62 – set in the 2017 Open at Royal Birkdale – when he played the first 14 holes in seven under par, only to miss from two feet for par on the 17th and have to settle for a 64.

Spieth had earlier breathed new life into his bid to become the sixth player to complete a career grand slam thanks to a 66, the 25-year-old having started the week by admitting he was "in a bit of a slump" after failing to record a top-20 finish all season.

Asked if the prospect of joining golf's most elusive club had crept into his mind, Spieth said: "It certainly hasn't. I can't imagine it will because I haven't been in contention on a Sunday since the Masters last year.

"If I'm able to put some good work in tomorrow, then I will be in contention on Sunday and at that point, it will be just more (thinking) of trying to win a golf tournament. It won't matter to me what tournament it is."

England's Matt Wallace shares fourth place with world number one Dustin Johnson, Daniel Berger and Kelly Kraft, although the quartet are eight shots off the pace, with Justin Rose another stroke back and Tommy Fleetwood on two under.

Rory McIlroy looked set to miss the cut when he limped to the turn in 40 after dropping five shots in his first three holes, but the four-time major winner produced a hat-trick of birdies from the fourth and picked up another shot on the eighth.

"I just needed to see one putt to go in, to see something hit the bottom of the hole and that was on the fourth," McIlroy said after making the weekend with nothing to spare. "From there I started to play some good golf.

"I had a horrendous start, five over after three, but came back well and the goal after those three holes was to be here for the weekend and it looks like I have done that, which is nice."

ga('create', 'UA-72310761-1', 'auto', {'name': 'pacontentapi'});
ga('pacontentapi.set', 'referrer', location.origin);
ga('pacontentapi.set', 'dimension1', 'By Phil Casey, Press Association Sport Golf Correspondent, Farmingdale');
ga('pacontentapi.set', 'dimension2', '74963266-2854-41c1-9bc5-e9c52ea1e180');
ga('pacontentapi.set', 'dimension3', 'paservice:sport,paservice:sport:uk,paservice:sport:world');
ga('pacontentapi.set', 'dimension6', 'story');
ga('pacontentapi.set', 'dimension7', 'composite');
ga('pacontentapi.set', 'dimension8', null);
ga('pacontentapi.set', 'dimension9', 'sport:golf,sport:other');
ga('pacontentapi.send', 'pageview', { 'location': location.href, 'page': (location.pathname + location.search + location.hash), 'title': 'Koepka sets 36-hole record as he extends lead over chasing pack at Bethpage'});