Dallas - Jason Kokrak rocketed up the leaderboard, firing a bogey-free 62 in the second round of the Byron Nelson as world No 1 Dustin Johnson shot a second straight 67 to remain in striking distance.
Kokrak, who is seeking his first win on the PGA Tour, fired a career-low eight-under-par round to forge his way into five-shot lead at 12-under 128 at the TPC Las Colinas course outside of Dallas.
"If a shot fits my eye or I see it, I like to pull the trigger," Kokrak said on Friday.
Former FedEx Cup and Tour Championship winner Billy Horschel shot a 65 on Friday and is alone in second at 133.
Half a dozen players - Johnson, Cameron Tringale (68), An Byeong-Hun of South Korea (66), Bud Cauley (67), Jhonattan Vegas of Venezuela (68) and first-round co-leader James Hahn (70) - are six shots back at 134.
Kokrak's round included eight birdies, a 12-foot par putt on the 10th hole and a seven-foot par putt on the 18th.
"Anytime you can have a bogey-free round on any golf course on the PGA Tour is awesome," Kokrak said.
"I made a lot of birdies out there and it was nice. I'm normally a pretty aggressive player and that's how I played today."
Johnson said he had to battle strong winds for the second straight round.
"This morning, the first nine holes we played the wind was howling, really blowing hard like it was yesterday the whole day," Johnson said. "But it kind of laid back with six holes to go.
"The game is still not quite as sharp as it was leading into Augusta, but it's getting there - it's getting close."
Defending champion and reigning Masters champion Sergio Garcia shot a 65 and moved back into contention at 138, while world No 6 Jordan Spieth shot a 75 on Friday and missed the cut.
Leading scores after the second round of the PGA Tour's Byron Nelson tournament (USA unless noted):
128 - Jason Kokrak 66-62
133 - Billy Horschel 68-65
- An Byeong-Hun (KOR) 68-66, Dustin Johnson 67-67, Cameron Tringale
66-68, Bud Cauley 67-67, James Hahn 64-70, Jhonattan Vegas (VEN) 66-68
135 - Peter Malnati 67-68, Grayson Murray 72-63, Morgan Hoffmann 69-66, Chad Campbell 68-67