Although two-time major champion Jordan Spieth is out of the AT&T Byron Nelson after firing a five-over 75 with a quadruple-bogey, tournament leader Jason Kokrak isn't comfortable entering the weekend even with a tournament-record five-stroke lead through 36 holes. 

Kokrak knows top-ranked Dustin Johnson is still lurking after he fired a 67 Friday in Irving, Texas to move into a T3 at 6-under par. 

"It's 36 holes. You've got the No. 1 player in the world chasing you, you've got x-number of other players that are outstanding players," Kokrak said. "Same game plan, just give myself birdie opportunities."

Kokrak (minus-12) has had a 36-hole lead now just twice in 146 career PGA Tour starts. He led the 2016 Northern Trust Open and ended up with a career-best tie for second.

Johnson enjoyed his second consecutive 67 and was tied for third with Byeong Hun An (66), Bud Cauley (67), Cameron Tringale (68), Jhonattan Vegas (68) and first-round co-leader James Hahn (70). 

Billy Horschel is second at 7 under while Masters champion Sergio Garcia birdied six of his last 15 holes for a 65 to get to 2 under, good for T25. 

Top-10 scores after Round 2 at par-70, TPC Four Seasons Resort:

Jason Kokrak 66-62—128
Billy Horschel 68-65—133
Byeong Hun An 68-66—134
Dustin Johnson 67-67—134
Cameron Tringale 66-68—134
Bud Cauley 67-67—134
James Hahn 64-70—134
Jhonattan Vegas 66-68—134
Peter Malnati 67-68—135
Grayson Murray 72-63—135
Morgan Hoffmann 69-66—135
Chad Campbell 68-67—135