By Mark Lamport-Stokes
LA QUINTA, California (Reuters) - Long-hitting American Jason Kokrak recorded two eagles in ideal scoring conditions as he charged into a three-way tie for the lead in Thursday's opening round at the Humana Challenge.
While twice former champion Phil Mickelson struggled with his putting en route to a level-par 72, Kokrak fired a flawless 63 at La Quinta Country Club, one of three venues hosting the pro-am celebrity event.
The beefy Kokrak took advantage of a picture-perfect day in the California desert, covering his last nine holes in four-under 32 to finish level with compatriots Roberto Castro and James Hahn.
In-form PGA Tour rookie Russell Henley, who won last week's Sony Open in Hawaii, was a further stroke back after a 64, along with fellow American Doug LaBelle II and Australians Aaron Baddeley and Greg Chalmers.
On a sublime, sun-splashed day in the California desert, Kokrak made a sizzling start with a birdie on his opening hole, the par-four 10th, followed by an eagle at the 11th.
"I just got off to a good solid start," he told reporters after mixing five birdies with his two eagles.
"I just tried to play solid from tee to green, put it in the right spots, put it in the fairways, and out there that's key. Today couldn't have been a better day."
Kokrak said he was feeling much more comfortable with playing conditions on the PGA Tour after completing his maiden season on the U.S. circuit in 2012.
"As a rookie out here last year I didn't know any of the golf courses, so coming out here now it's a little bit more relaxed," he added. "It's easier for me to get into a little bit of a routine.
"I don't have to go out there and learn every little detail. I can come out here and just concentrate on my game."
Castro, who started out on the Nicklaus Private course, birdied his first two holes before surging into a share of the lead with five birdies on his homeward nine.
"I got off to a good start, birdied the first two with kick-ins basically, and then just played well after that," the 27-year-old said.
"I didn't make any long putts until the 18th hole where I rolled in like a 40, 50-footer. This tournament, you kind of got to get it going and keep it going. If you don't make a bunch of birdies you're kind of left behind."
While most of the players in the field made the most of the low-scoring conditions, Mickelson struggled on the greens as he battled flu-like symptoms for a 11th consecutive day.
"My expectations were to be really low today but I putted terrible," Mickelson, tournament winner in 2002 and 2004, said after totaling 30 putts on the La Quinta layout.
"I had a bunch of six-footers I missed, my rhythm was off."
Also making a poor start to the third event on the 2013 PGA Tour was fellow American Mark Wilson, the defending champion, who labored to a five-over 77 at La Quinta.
(Reporting by Mark Lamport-Stokes; Editing by Frank Pingue)