Britain's Luke Donald fired a four-under-par 66 in the second round to take a one-shot lead at the $6.3 million Byron Nelson Championship.

Donald, with a 36-hole total of 133, holds the lead over defending champion Brett Wetterich, Swede Fredrik Jacobson and first round leader Sean O'Hair.

"Coming into this week, I felt good about my game and was really swinging well," said Donald.  "This really sets me up well for the weekend."

Donald birdied the first hole at the TPC course and picked up strokes on the 5th, 7th and 12th. He suffered his first bogey of the week on the par 4 14th but came back with a birdie at the par 5 16th

Wetterich said he felt he was in good shape at the event, which he won last year by a single stroke for his first Tour win.

"I've heard the saying, 'horses for courses.' I don't know if I'm the horse for this course, but I do enjoy it," he added.

Wetterich is attempting to become the first player since Tom Watson (1978-79-80) to win the tournament in successive years.

"That would be a nice piece of trivia," Wetterich said.

"I wouldn't mind my name being in there with his. I feel like I'm a better player than last year. It's a work in progress, but it's going in the right direction."

He enjoyed a bogey free round, hitting 14 of 18 greens in regulation.

Jacobson said he was glad to be back in action after surgery on his right wrist last year put him out for seven months.

"I hit the ball better today but I just want to play golf," said the Swede.  "I need to play and I have a pretty heavy schedule as long as the wrist is OK."

World number seven Vijay Singh returned a 67 for a tally of 136.

Amateur Colt Knost had the low round of the day, a six-under 64, the lowest round ever shot by an amateur at the event.

American Kent Jones shot a four-under 66 to stand two shots behind the leaders at 135, tied with Scott Verplank who shot a two under 68.