American Jason Kokrak put himself in a great position to win a first PGA Tour title at the AT&T Byron Nelson as Jordan Spieth had a day to forget.
Kokrak fired a stunning 62, just two shots more than the course record, to move five clear in the lead on 12 under at the halfway point at TPC Four Seasons.
The 31-year-old sank eight birdies in his blemish-free round and he will now aim to complete the job over the weekend and get his first taste of success on the tour.
Ireland's Seamus Power booked his place for the weekend as a second successive round of 69 left him on two under par, tied for 25th but 10 shots off the lead.
One man who will not be around for the weekend, though, is Spieth after he missed the cut following a bogey-laden 75.
It was on the par-five 16th where the real damage was done as he had to take three tee shots on his way to a nine after sending his first two attempts out of bounds.
"Just disappointed," said Spieth. "I've got to figure out what I'm doing on the greens, first and foremost. I've got to get back into rhythm there. Short game is just off (but) it's close."
Kokrak, who has not finished in the top 10 of an event this year, is being hunted down by Billy Horschel, who is five shots back on seven under.
The stocky Kokrak may need the added cushion as the chasing pack includes world number one Dustin Johnson, who shot his second 67 to be six-under on 134.
"All week I've been feeling better and better with the putter," said Kokrak. "Dave Stockton, Jr. and his dad have helped me out the last few weeks and things are starting to kind of go in an upturn."
Reigning champion and recent Masters winner Sergio Garcia is also 10 shots back after a superb round of 65, recovering from what was a poor first round.
