DALLAS, May 16, 2014 (AFP) - Hanson didn't let his unfamiliarity with the TPC Four Seasons course bother him as he nabbed six birdies with just one bogey for a one-shot lead over Australian Marc Leishman, New Zealand's Tim Wilkinson and American David Duval.
"Always nice to get off to a fast start," said Hanson, who joined the US tour full time last season and is seeking his first win on the tour.
He fired a blistering 30 on the front nine, where he made five of his six birdies, coming home in even par with a bogey balanced by a birdie at 18.
"I got off to a really good start, had a few chances coming back in and made a bit of a clumsy bogey from the fringe on 14, but those things happen," said the Swede, who pulled out of the Wells Fargo Championship at Quail Hollow a fortnight ago with a back injury.
Leishman set the early pace in the Dallas suburb of Irving with what he called a "fairly stress-free" round.
He got it going with a birdie at the 206-yard, par-three second hole, where his tee shot left him a tap-in from a foot away.
"It was a good surprise," said Leishman, who couldn't see the flight of the ball. "I thought I hit a good shot, but it's hard to tell when you're looking straight into the sun."
He picked up another birdie at the third before his only bogey of the day at the par-four fourth -- which was promptly followed by a birdie at the par-three fifth.
Two more birdies coming in put Leishman at four-under.
He was joined there by Wilkinson, whose five-birdies included three in a row starting at the fourth, and Duval, who teed off at the 10th and capped his round with three straight birdies at the seventh, eighth and ninth.
Duval almost pulled out of the tournament because of pain in his right elbow. His decision to play paid off as he twice holed out from the fairway.
"I'm lucky to have had it feel better as the day went on," Duval said of his elbow. "Not 100 percent by any stretch, but 1,000 percent better than it was."
Germany's Martin Kaymer, winner of the Players Championship on Sunday, headlined a group of eight players on three-under 67. He was joined by South African Tyrone Van Aswegen, fellow German Alex Cejka and Americans Boo Weekley, John Huh, Alex Prugh, Ryan Palmer and Lee Williams.
Leading first-round scores on Thursday in the US PGA Tour $6.9 million Byron Nelson Championship (USA unless noted, par-70):
65 - Peter Hanson (SWE)
66 - Marc Leishman (AUS), David Duval, Tim Wilkinson (NZL)
67 - Ryan Palmer, Boo Weekley, John Huh, Tyrone Van Aswegen (RSA), Alex Cejka (GER), Martin Kaymer (GER), Alex Prugh, Lee Williams
68 - Tim Herron, Brendon Todd, Louis Oosthuizen (RSA), Charles Howell, Aaron Baddeley (AUS), Rod Pampling (AUS), Eric Axley, Jason Allred, Graham DeLaet (CAN), Morgan Hoffmann, Gary Woodland, Ryan Moore, Mike Weir (CAN), Padraig Harrington (IRL), Ben Crane, Miguel Angel Carballo (ARG)