American Sean O'Hair fired a five-under-par 65 to take the first round lead at the $6.3 million Byron Nelson Championship.

Defending champion Brett Wetterich and Denmark's Anders Hansen were a shot back in second place at four under. Luke Donald and Scott Verplank were in a group of five players a stroke further back.

O'Hair, who finished second in the event a single adrift of winner Ted Purdy in 2005, played the Cottonwood Valley course, one of two courses being used, at the Four Seasons Resort.

"I felt really good with my ball striking today. I started the putts on my line and it was really just a good round of golf," O'Hair said.

O'Hair mixed seven birdies with two bogeys to take the 18-hole lead under sunny skies and light winds.

"I like this course and I like being back in Texas," he added. "I like the food here, the weather, and the people. It's almost like being back at my second home."

His second place finish here in 2005 gave him the confidence to gain his maiden win at the John Deere Classic in July that year, but in 2006 he slipped more than 40 spots on the money list.

"I'm back with my old teacher after parting with him right before my first win. Than I spent a year and a half working on my backswing before I figured out that didn't really make much different," he said.

O'Hair has shot level-par or better in 11 of his last 12 rounds and has four top 15 finishes in his last five tournaments.

Dane Hansen, in his first full year on the PGA Tour, said it had been tough to adjust from Europe.

"I'm pleased with my round today, but it's been tough because I don't know these courses like I do the ones in Europe," he said.

Briton Donald had a bogey free round at Cottonwood Valley, while Verplank bogeyed the par 4 5th but had birdies at the 8th, 10th, 16th and 17th.