Updated

La Jolla, CA (SportsNetwork.com) - Jordan Spieth fired a 9-under 63 on Friday to soar into the lead after two rounds of the Farmers Insurance Open.

Spieth, who played alongside seven-time champion Tiger Woods, ended 36 holes with a one-shot lead at 10-under-par 134.

Former British Open champion Stewart Cink, the first-round leader, carded a 1- under 71 on the more difficult South Course at Torrey Pines and dipped into second place at minus-9.

Nicolas Colsaerts posted a 5-under 67 on the South Course and climbed into third place at 8-under-par 136.

Billy Horschel had a 67 on the North Course and moved into a share of fourth at minus-7. He was joined there by Marc Leishman, who carded a 1-under 71 on Friday.

Gary Woodland (73), Pat Perez (71), Erik Compton (69), Russell Knox (67) and Morgan Hoffmann (66) shared sixth place at 6-under-par 138.

Woods, the defending champion, managed a 1-under 71 and finished two rounds tied for 50th at 1-under-par 143.

Phil Mickelson, a two-time winner of this event, stumbled to a 1-over 73 and he dipped into a share of 32nd at minus-2.

Woods, who started on the back nine on the North Course, opened with a birdie on the 10th then moved to 2-under with a birdie on the 15th. After 11 consecutive pars, he faltered to a bogey on the par-5 ninth.

"I was a yard off, a foot off all day and it was one of those frustrating rounds because balls were landing in the fairway, running a foot in the rough and then I couldn't be aggressive," Woods said. "I couldn't get after some of these flags and consequently my score reflected that."

Mickelson, who is playing with a sore back, got off to a slow start he bogeyed the third, fifth and seventh to go with a birdie on the par-5 sixth. He got another shot back when he birdied the par-5 ninth.

After four straight pars, Mickelson wrapped birdies at 14 and 16 around a bogey on the 15th. He was back to even-par for his round, but made a mess of the 18th and walked off with a closing bogey.

Mickelson said he was "unsure" whether he'll play or withdraw due to his back problems.

"I love this tournament and I want to play here, I love playing in San Diego and this is a place where I grew up playing, so I really want to play," he said. "And part of me also says that I'm getting in bad habits and if I hit it in this rough here, I've really got an issue because I've got to swing awfully hard to get it out and it jars it, so I'm a little torn right now on the best plan of action."

Spieth was hot from the start on the North Course. He started with a birdie on the 10th and made consecutive birdies at 13 and 14 to move to minus-4. He picked up another stroke on No. 18.

Last year's Rookie of the Year got up and down for birdie at the par-4 second and stuffed his approach at the fourth, kicking that in for birdie.

He followed with a 3-foot birdie effort on the fifth and made it three in a row as his long birdie putt on No. 6 found the bottom of the cup.

That spurt gave Spieth a piece of the lead with Leishman and Cink. After Cink moved ahead, Spieth answered with a 10-foot birdie putt on No. 8. The duo stood at 10-under, and Spieth parred the last to remain there.

"Today was obviously a round that I enjoyed very much. You know, tee to green I actually hit the ball a little better yesterday than I did today, I just putted extremely well today," Spieth said. "Found something that I needed to work on and I got a little more stable in my address and I felt comfortable over my putter the whole day."

Cink had eight pars and a lone birdie on his opening nine on the South Course. Around the turn, he birdied the first to get to 10-under. After Spieth's round was over, Cink fell off the pace.

The 2009 British Open champion tripped to a bogey on No. 5. Cink fell two back as he 3-putted for bogey on the par-3 eighth. He bounced back with a 15-footer for birdie on No. 9 to end one behind.

Leishman had three birdies in a 4-hole span from No. 13 to gain a piece of the lead at minus-9. He reeled off six pars in a row before tripping to a double- bogey on the fifth. Leishman parred his final four holes to end three back.

NOTES: Spieth owns the 36-hole lead for the second time in his PGA Tour career ... For only the sixth time in his PGA Tour career, Woods has failed to record a birdie on a par-5 through 36 holes ... The cut line fell at even-par 144 with 83 players making it to the weekend. There will be a secondary cut to the closest number to 70 after the third round ... Among those who failed to make the cut were Jimmy Walker, Geoff Ogilvy, Vijay Singh, Rickie Fowler, Brandt Snedeker and Russell Henley.