South Korean Charlie Wi birdied three of his last six holes to grab an early two-shot lead in Friday's second round of the Pebble Beach National Pro-Am as Tiger Woods finished six strokes off the pace.

Wi, one of three players tied for the lead overnight, fired a three-under-par 69 at Pebble Beach Golf Links, one of three venues being used this week, to post a 12-under total of 130.

In pursuit of his first PGA Tour victory, Wi eagled the par-four 13th, his fourth hole of the day, before ending his round in topsy-turvy fashion birdie-bogey-birdie-par-birdie-bogey.

American world number 10 Dustin Johnson, tournament champion in 2009 and 2010, was alone in second after carding a 72 on the tricky Spyglass Hill layout.

Fijian Vijay Singh, who returned a 68 at Spyglass, was a further two shots back at eight under with New Zealander Danny Lee (73) and American Brian Gay (65).

Woods, however, was left frustrated after shooting a two-under 68 at Monterey Peninsula, the easiest of the three layouts.

"It was decent," the former world number one told Golf Channel after finishing his round in steady drizzle and plunging temperatures. "I drove it good again today, unfortunately I just didn't make enough birdies.

"The hard part was just getting the ball in there (on the greens) where you could give it a free run. I was hitting the ball in wrong spots.

"I am six back so I need to make something happen a little bit over there," Woods added, referring to his third round on Saturday at Pebble Beach Golf Links.

Three-times winner Phil Mickelson carded a 65 at Monterey Peninsula to finish five strokes off the lead, level in a large group with fellow U.S. Ryder Cup player Hunter Mahan (70).

(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Julian Linden)