Hahn and Castro were 14 under after another day of perfect conditions in the Coachella Valley. They began the round tied for the lead with Jason Kokrak at 63.

Hahn had four birdies, an eagle and a bogey at La Quinta Country Club. He played a three-hole stretch in 4 under on his back nine, birdieing the par-4 fourth, holing a 30-foot eagle chip on the par-5 fifth and making another birdie on the par-5 sixth.

“Any time you have back-to-back par 5s that are reachable, it’s definitely something to look forward to,” Hahn said. “Especially if the round’s not going well.”

Castro had the lead alone at 16 under, but bogeyed two of his last three holes — three-putting the par-4 ninth — on PGA West’s Arnold Palmer Private Course.

“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 opened his rookie season on the tour last week in Hawaii with a tie for 67th in the Sony Open. The 31-year-old South Korean-born American played briefly at the University of California and won the Web.com Tour’s Rex Hospital Open last year in a playoff.

“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.”

Castro missed the cut last week in Hawaii. The 27-year-old former Georgia Tech player is in his second season on the tour.

“They had a lot of Sunday pins today,” Castro said. “I only played here one time, but the pins they used today were a lot of the ones they used Sunday last year. So I think Palmer was playing pretty tough. There were a lot of tucked pins.”

The stats agreed with the Palmer course having the highest scoring average in the first two rounds at 69.596. LaQuinta was next at 69.529, and the Nicklaus course the lowest at 67.923.

Darron Stiles, Scott Stallings and Richard H. Lee were 13 under, all shooting 65. Stiles and Stallings played at La Quinta, and Lee was on the Palmer course.

Kokrak had a 69 on the Nicklaus course to drop into a tie for sixth at 12 under.

Phil Mickelson shot a 67 on the Nicklaus course after opening with a 72 at La Quinta. The tournament winner in 2002 and 2004, he was nine strokes behind the leaders and two strokes off the projected cut Saturday.

“The last two holes were the first time that I actually hit solid shots and my rhythm felt good and I made good wings,” 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.”

The tournament is his first since tying for second in early November in the HSBC Champions in China, the only event he played after the Ryder Cup. He plans to play five or six straight events, a run that will end at Riviera or the Match Play Championship.

“I really want to build some momentum here on the West Coast,” Mickelson said.

Russell Henley, the Sony Open winner Sunday in his first start as a PGA Tour member, had a 69 at the Palmer course to reach 11 under. He shot a 64 on Thursday at the Nicklaus course, and is 35 under in his first six rounds this year.

Matt Kuchar, paired with Mickelson, had a 64 — matching the best round of the day — to get to 10 under. He’s playing for the third straight week.

“It certainly helps playing the last couple of weeks,” Kuchar said. “My first week out at the Tournament of Champions there was definitely some rust and lack of scoring. Even if you have been practicing, which I was, tournament play is just a little bit different.”

DIVOTS: Mike Weir, the 2003 champion, followed his opening 67 at La Quinta with a 75 at the Nicklaus course to drop into a tie for 130th in the 156-man field at 2 under. The Canadian has missed 16 consecutive cuts and finished only one tournament — a tie for 70th in the AT&T National in July 2011 — in his last 28 events. The top 70 and ties after the third round Saturday will play Sunday at the Palmer course. … FedEx Cup champion Brandt Snedeker shot a 68 on the Nicklaus course to reach 9 under. He’s the highest-ranked player in the field at No. 8. … Defending champion Mark Wilson was tied for 138th at 1 under after a 66 on the Nicklaus course. He opened with a 77 at La Quinta.