Brooks Koepka sent records tumbling as he took a stranglehold on the US PGA Championship after 36 holes at Bethpage State Park BK Course.
The defending champion followed up his opening 63 with a 65 to get to 12 under and establish a seven shot lead over Australian Adam Scott and American Jordan Spieth.
England's Matt Wallace was then eight shots off the lead alongside World Number One Dustin Johnson and his fellow Americans Daniel Berger, Kelly Kraft and Luke List.
Koepka's 128 shots is the lowest 36 hole total in Major history, while 12 under is the lowest score to par ever at the US PGA Championship after 36 holes.
The leading margin is also a record for the halfway stage at this event as Koepka looks for a fourth Major to go with his triumph at Bellerive Country Club and back to back victories at the U.S. Open in 2017 and 2018.
Bethpage Black is widely regarded as one of the toughest layouts in the world and while it has lived up to its reputation for most of the field, American Koepka - attempting to make it four wins from the last nine Majors - has been on another level.
"Today is a new day," he said. "It doesn't matter what you did yesterday, you just need to go out there and post a good score and I did that today. I'm very pleased. It's a tough golf course, you've really got to battle and I'm proud of the way I hung in there today.
"You've just got to let things roll off your back. You look at the bogey on ten and three putt on 17, you just need to let things go, laugh about it and move on. If you start dwelling on it, this is a major test of your patience.
I'll just keep doing what I'm doing, put the pedal down, try to create a bigger lead and go from there - Brooks Koepka
"I'll just keep doing what I'm doing, put the pedal down, try to create a bigger lead and go from there."
Koepka entered the day with a one shot lead at seven under but that was increased to four as Danny Lee fell back before Spieth emerged as his nearest challenger.
The three time Major Champion - seeking a career grand slam this week - turned in level par but then birdied the first, fourth, seventh and eighth in a 66 that set the clubhouse target two off the lead.
But Koepka was relentless in the afternoon, leaving himself just 59 yards for his approach into the first and and a ten foot putt on the second for a birdie-birdie start.
When he got on the par five fourth in two and down from 17 feet in two putts, he led by five, but he bogeyed the tenth and his lead was briefly cut to three by the charging Scott.
The 2013 Masters Tournament Champion made birdies on the first, second, third, fifth and 11th thanks to a remarkable 137 feet and three inches of putts in his first 12 holes.
Excellent approaches into the 13th and 14th had him seven under for the day but Koepka then found another gear.
The 29-year-old got on the par five 13th in two with two enormous hits to get back to double figures, and then put approaches to inside six feet on the 15th and 16th.
Scott made a three putt bogey on the 17th and it was Wallace who emerged as Koepka's closest rival as he made six birdies in seven holes from the 18th, with the help of a 48 foot putt on the second.
But the four time European Tour winner bogeyed the seventh and eighth in a 67 and, while Koepka three putted the 17th, he hit back from 11 feet on the last.
Kraft carded a 65, one shot better than Berger, with Johnson signing for a 67 and List a 68.
Justin Rose was then at three under, a shot clear of a group containing Tommy Fleetwood, Jazz Janewattananond, Louis Oosthuizen and Erik van Rooyen.
