Jan 24 (Reuters) - Jordan Spieth totally upstaged playing partner and defending champion Tiger Woods as he charged to the clubhouse lead in Friday's second round of the Farmers Insurance Open outside San Diego.
American Spieth, one of the most exciting young players in the game who was the PGA Tour's Rookie of the Year in 2013, fired a flawless nine-under-par 63 on the easier North Course at Torrey Pines, one of two venues hosting the event.
Spieth, helped by a slight adjustment to his putting technique since the opening round, covered his back nine in five-under 31 in calm, mainly overcast conditions on the coastal layout to post a 10-under total of 134.
World number one Woods, seeking an eighth victory at this tournament, failed to birdie a single par-five for the second day in a row as he carded a 71 to finish a distant nine strokes off the early lead.
American Billy Horschel fired a 67 on the North Course to sit three strokes behind Spieth, ending at seven under with Australian Marc Leishman who carded a 71 on the brutally difficult South Course.
Overnight pacesetter Stewart Cink, who had opened with a bogey-free 64, was among the day's late starters and level with Spieth at 10 under with five holes to play.
Spieth, who clinched his maiden PGA Tour title at last year's John Deere Classic during a sensational debut season on the U.S. circuit, was delighted with the improvement in his putting on Friday.
"I changed it a little bit, put my weight a little more on my front foot today," the 20-year-old told Golf Channel. "I had noticed that was kind of causing a little bit of a tendency to push it on the shorter putts for me.
"So I was more stable with the ball and I plotted my way around an easier golf course in some nice conditions."
Asked how he had managed to cope with the huge crowds and heightened media focus while playing in a group that included 14-times major champion Woods, Spieth replied: "I've spent a lot of time with him.
"It wasn't the first time I had teed it up next to the guy I've watched growing up. He is easy to play with, he talks to us. Similar to Jimmy (Walker, the third member of the group), they are both very easy, fun guys to play with.
"We played with some good speed, kept the tempo up and I just played my game ... didn't even see a scoreboard and really didn't know where I was at until I got to number nine. That's the way you want it to be out there when you're in the zone."
Woods, competing in his first tournament of the year, was most certainly not in the zone as he recorded only two birdies and a bogey in ideal scoring conditions.
His bogey came on his final hole, the par-five ninth, after he hit his tee shot into the right rough and he declined to give Golf Channel an interview after signing his card.
The cut was projected to fall at level-par 144 with Fiji's former world number one Vijay Singh and 2012 champion Brandt Snedeker among those unlikely to advance. (Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Gene Cherry)