* Barnes equals course record with a sizzling 64
* Chinese teenager Guan opens with a level-par 72 (Updates at end of round)
April 25 (Reuters) - Long-hitting American Ricky Barnes made a welcome return to form after two months of struggle as he charged into a one-shot lead in Thursday's opening round of the Zurich Classic of New Orleans in Avondale, Louisiana.
The 32-year-old, who is bidding for his first victory on the PGA Tour, took advantage of receptive, rain-softened conditions at the TPC Louisiana to fire a sizzling eight-under-par 64.
With players permitted to lift, clean and replace golf balls on the fairway after more than an inch of rain had saturated the layout on Wednesday, Barnes birdied six of his last eight holes to tie the course record.
Boo Weekley and former U.S. Open champion Lucas Glover also made the most of the low-scoring conditions with opening 65s, finishing a stroke in front of fellow Americans D.A. Points and PGA Tour rookie Morgan Hoffmann.
Four-times major winner Ernie Els was among a group of 10 players on 67, while defending champion Jason Dufner, who clinched last year's title in a playoff with South African Els, launched his defence with a level-par 70.
China's 14-year-old prodigy Guan Tianlang also flourished in the opening round, upstaging several big names as he rebounded from two early bogeys to card a level-par 72.
Competing this week on a sponsor's exemption, Guan has been one of the biggest talking points in golf after becoming the youngest player to make the cut in a major championship at the Masters earlier this month.
Barnes, however, commanded most of the early spotlight as he shrugged off memories of seven missed cuts in his last eight starts on the PGA Tour after beginning the season in reasonably good form.
He eagled the par-five second before reaching the turn in two-under 34, then stormed home in six-under 30 to surge to the top of the leaderboard.
"It was good today," Barnes told Golf Channel after piling up seven birdies along with his eagle and a lone bogey at the sixth. "It has been a long past two months, especially after starting off so well in Hawaii and Palm Springs.
"I was really hitting the ball pretty well early on on the West Coast (swing)."
Barnes, whose best PGA Tour finish was joint second at the 2009 U.S. Open, tied for 20th at the Sony Open in Hawaii and shared 16th place at the Humana Challenge before his 2013 campaign unravelled.
"I started working on stuff and it just wasn't clicking for me," he said. "I knew I was going in the right direction with what I was working on. I just wasn't grasping it and the results weren't giving me any confidence as well.
"Good shots usually lead to confidence and I wasn't really hitting it good and I wasn't swinging good. And the short game wasn't very good.
"I have been working pretty hard on all aspects of the game for the past two months, especially on the short game ... and today it kind of proved that is starting to pay off."
Weekley, who won the most recent of his two PGA Tour titles at the 2008 Verizon Heritage, was in an upbeat mood after recording three birdies in his last five holes.
"It was good, it could have got real good if some of them putts would have fell early in the round," said the laid-back Floridian, who is known for his love of shooting and fishing. "I just felt good over it today."
World number four Justin Rose, the highest-ranked player in the field, opened with a 68 while last year's Masters champion Bubba Watson, who clinched the New Orleans title in 2011, battled to a three-bogey 73. (Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Frank Pingue and Greg Stutchbury)