Peter Hanson takes early lead at Byron Nelson Championship

Two weeks after withdrawing from the Wells Fargo Championship with a back injury, Swede Peter Hanson charged into a one-shot lead at the Byron Nelson Championship on a course he barely knows on Thursday.

Hanson, despite having seen only the front nine at the TPC Las Colinas in practice, piled up six birdies and a sole bogey to card a five-under-par 65 in breezy conditions in Irving, Texas.

The 36-year-old stormed to the turn in five-under 30, then offset a bogey at the 14th with a birdie at the last to finish a stroke in front of Australian Marc Leishman, New Zealand's Tim Wilkinson and American former world number one David Duval.

Germany's Martin Kaymer, fresh from victory at the Players Championship on Sunday, and American Ryan Palmer were among a group of eight players knotted on 67, while Pádraig Harrington birdied the final two holes of his opening round to card a two-under 68.

Hanson, a six-times winner on the European Tour who has yet to taste victory on the PGA Tour, was delighted with his opening 65.

“It’s always nice to get off to a fast start,” the Swede told reporters after hitting a nine-iron approach to six feet at the par-four 18th to set up his sixth birdie of the day.

“I gave myself a few chances on the back (nine), made a bogey on 14 from the middle of the fairway and had a reasonable chance to make a birdie on 16.

“It was nice to get off with a birdie at the last. With the greens and how small they are and the run-off areas, if you start missing greens you get some very, very difficult lies and up and downs. Once you start chipping, you will make bogeys.”

Duval, who plays a limited schedule on the PGA Tour, surged up the leaderboard with four birdies in his last five holes after very nearly withdrawing from the tournament earlier in the day because of pain in his right elbow.

“I’m tickled pink it feels as good as it does right now,” Duval, who has not won on the PGA Tour since his sole Major victory at the 2001 British Open, said of his elbow.

“It was not good, and you know, I’m not getting to play a whole lot right now. It would’ve been a hard thing to swallow not to be able to tee off.”

Defending champion Bae Sang-moon of South Korea did not enjoy the best of starts, mixing five birdies with six bogeys and a double at the par-four eighth to card a three-over 73.

Local favourite Jordan Spieth, who played with Bae in a high-profile grouping that also included his fellow American Harris English, opened with a 70. English returned a 71.

After missing the cut at the Wells Fargo Championship last time out, Harrington picked up three birdies in his first seven holes before dropping a shot at the par-three 17th after missing his par putt from nine feet.

A bogey on the first was offset by a birdie on the the 221-yard par-three second when he rolled in his putt from 22 feet.

Back-to-back bogeys on the fifth and sixth dropped him back to level par before approach shots to seven and six feet at the final two holes saw him end the day in a share of 13th spot on two under.