DALLAS, Texas, May 18, 2012 (AFP) - Dufner finished off his round with a 37-foot chip-in at the 429-yard 18th. His drive off the tee sailed wide right and he hit an approach that rolled over the green.
"I'm confident with my game and happy with where my game is right now," he said.
Dufner, who won last month in New Orleans for his first USPGA Tour title, reached seven-under 133. He also had a 35-foot chip in at the 15th hole.
He had the 36-hole lead at the Masters, one of four times Dufner has led after two rounds this season.
Because he has won before after leading at the halfway point of a tournament, Dufner feels he can do it again.
"It was a nice way to finish, looking forward to the weekend," Dufner said.
"I was kind of around par for the day, trying to stay patient a little bit, maybe get a birdie or two on the last five holes and ended up getting birdie on four of the last five, couple of chip-ins, which you don't expect, especially the one on 18.
"That's a difficult position to be over the back of that green to that hole location.
Matt Kuchar was second along with first-round leader Ryan Palmer, Chad Campbell, Pat Perez, Dicky Pride and Marc Leishman.
Kuchar shot a 68 and is fresh off a win at The Players Championship on Sunday.
Phil Mickelson, who is one of just two top 10 players in the field, finished with a double bogey for a 69. He was not happy with his round.
"I hit it terrible today, there was no other way around it," Mickelson said. "I've just got some mechanical issues where I was not striking the ball very solid. I was able to hit decent shots on the backside to make birdies and make a run, but that last hole stunk."
Kuchar has a chance to become the first PGA Tour player since Tiger Woods three years ago to win in consecutive weeks. Woods also was the last player to win in his next start after winning The Players Championship. He did it in 2001.
Leading scores on Friday after the second round of the $6.5 million PGA Tour Byron Nelson Championship (USA unless noted, par 70):
133 - Jason Dufner 67-66
134 - Chad Campbell 68-66, Matt Kuchar 66-68, Marc Leishman (AUS) 65-69, Ryan Palmer 64-70, Pat Perez 67-67, Dicky Pride 66-68
135 - Keegan Bradley 67-68, Charley Hoffman 66-69, Ryuji Imada (JPN) 67-68
136 - Jason Day (AUS) 68-68, Ken Duke 69-67, J.J. Henry 68-68, Scott Piercy 66-70
137 - Blake Adams 66-71, Padraig Harrington (IRL) 68-69, Billy Mayfair 69-68, D.A. Points 68-69, Boo Weekley 69-68