Castro, Hahn stay on top in La Quinta

Roberto Castro and rookie James Hahn both carded a 5-under 67 on Friday to retain a share of the lead after two rounds of the Humana Challenge.

Castro and Hahn, who are both seeking their first PGA Tour victory, sit at 14- under 130 through 36 holes. Darron Stiles, Scott Stallings and Richard H. Lee all fired 65 and moved into a tie for third place at minus-13.

"I'm just soaking it in, having a good time," Hahn said. "Any time that I play a good round, it feels good and makes me cherish the momentum a little bit more, because I know they're few and far between."

Jason Kokrak shared the first-round lead with Castro and Hahn, but he shot 69 on Friday and fell into a tie for sixth place with eight others, including Zach Johnson, at 12-under.

Phil Mickelson improved on the second day after carding an opening-round 72 in his season debut. The lefty, who is recovering from flu-like symptoms, carded seven birdies against a pair of bogeys en route to a 67 on Friday.

"The last two holes were the first time that I actually hit solid shots and my rhythm felt good and I made good swings," Mickelson said. "I've been quick from the top. My rhythm has been off and I've hit a bunch of squirrelly shots. I made a lot of rusty mistakes."

Rookie Russell Henley is looking to become the first rookie in PGA Tour history to win his first two starts. The Sony Open in Hawaii victor has recorded rounds of 64 and 69 -- good for a 15th-place tie at minus-11.

Defending champion Mark Wilson stumbled to an opening-round 77 before recovering with a 66 on Friday. He is 1-under through 36 holes.

Last year's Players champion Matt Kuchar is 10-under through 36, world No. 8 Brandt Snedeker is 9-under and 2012 U.S. Open champion Webb Simpson is 1- under.

Three different courses are in play during the first 54 holes of this tournament -- the Palmer Private Course and the Nicklaus Private Course at PGA West, and La Quinta Country Club -- with the final round taking place at Palmer Private.

Castro, who tied for 42nd place at this event as a rookie in 2012, rattled off seven birdies at Palmer Private on Friday. He had sole possession of the lead at 16-under during his outward nine, but he closed with two bogeys in his final three holes to fall to minus-14.

"A couple slipped away there at the end, but yesterday I made a 50-footer on the last," Castro said. "Today, I felt like I hit a good putt and three- putted. So, that's stuff over 72 holes that's going to even out."

Hahn earned his PGA Tour card by finishing fifth on the 2012 money list and he has made the most of the opportunity thus far. The 31-year-old rookie played La Quinta on Friday and highlighted his round with a birdie, eagle, birdie stretch beginning at the par-4 fourth. His eagle came courtesy of a 30-foot chip-in on the par-5 fifth.

Still, the odds are against Hahn, as only three players -- Jhonattan Vegas (2011), Arnold Palmer (1960) and Charley Hoffman (2007) -- have won the Humana Challenge in their first start at the event.

NOTES: Hahn's only start on the PGA Tour prior to 2013 ended in a missed cut at the 2012 U.S. Open ... Castro's lone top-10 finish in 2012 was a tie for seventh at the Greenbrier Classic ... The cut will come on Saturday after every player has navigated each of the three courses.