Jason Kokrak has opened up a five-shot lead at the halfway stage of the AT&T Byron Nelson in Texas.
The American hit eight birdies during a faultless round of 62 to hold a clear advantage heading into the weekend.
Billy Horschel sits in second position, while world number one Dustin Johnson holds a share of third place after a second successive round of 67.
Jason Day, Jason Dufner and Matt Kuchar all feature inside the top 20, with Spain's Sergio Garcia further down the standings in 25th spot.
Ian Poulter - who finished in a tie for second at last week's Players Championship - made the cut after he birdied the final hole to ensure that he entered the weekend in 60th.
However, Jordan Spieth missed out after a 75 on Friday left him below the cut line.
