LEADERBOARD -8 K Stadler (US) -7 J Parnevik (Swe), T Purdy (US) -6 K Sutherland (US), M Gronberg (Swe), C Barlow (US), B Tway (US), T Lehman (US)

Stadler finished a shot clear of Ted Purdy and Sweden's Jesper Parnevik at Torrey Pines North course.

Two shots back were Kevin Sutherland, Sweden's Mathias Gronberg, Craig Barlow, Bob Tway and Tom Lehman.

Defending champion Tiger Woods shot 71 on the more difficult South course, while Vijay Singh also carded 71.

Northern Ireland's Darren Clarke finished at two under, shooting three birdies and a bogey in his round of 70.

Stadler, who watched his father win at Torrey Pines 10 years ago, was stunned by his own feat.

"I've been playing well, but I would never have dreamed of this," he said.

Stadler played with his father last week at the Pebble Beach National Pro-Am, where he made the cut for the first time in five PGA Tour events.

I feel certain people think I'm just playing because of my dad, and I want to shed that Kevin Stadler

He has failed to get past the first stage of qualifying school twice, and required a sponsor's exemption to the Buick.

Stadler admits he is more known for his famous father - nicknamed the "Walrus" - than his own achievements.

"You get a look-a-like comment about every four feet wherever I go," he said.

"I don't know if that's a good thing or a bad thing, but it will never go away unless I do something about it."

The North course was playing 3.8 strokes easier than the South on Thursday.

Hal Sutton was the only player among the top 27 on the leaderboard to play the South, with Woods bemused by his own first-round effort.

"They said I was fourth on this golf course and 57th in the tournament," he said.

By the end of the day Woods was in a tie for 63rd, and 11 players had better scores on the South.

"Everyone is tearing up the North, so I need to do the same thing," Woods added.

Singh, coming off his victory at Pebble Beach on Sunday, could only manage a 71 however on the North course.