1 / 12

Jason Dufner chips onto the 16th green during the second round of the PGA Byron Nelson Championship golf tournament Friday, May 18, 2012, in Irving, Texas. Dufner finished with a two-round score of 7-under-par (AP Photo/Tony Gutierrez)

Jason Dufner chips onto the 16th green during the second round of the PGA Byron Nelson Championship golf tournament Friday, May 18, 2012, in Irving, Texas. Dufner finished with a two-round score of 7-under-par (AP Photo/Tony Gutierrez)

Byron Nelson Championship

Jason Dufner chipped in from 37 feet, his fourth birdie in five holes, for a one-shot lead after two rounds of the Byron Nelson Championship in Irving, Texas.