By Mark Lamport-Stokes

PACIFIC PALISADES, California (Reuters) -

Twice champion Phil Mickelson doubled his overnight lead to two shots early in Friday's second round of the Northern Trust Open without playing at his best.

Jimmy Walker, who teed off in the first group of the round from the par-four 10th, fired a six-birdie 66 to finish at four under, level with fellow American Matt Kuchar (69) and Swede Carl Pettersson (70).

"I probably didn't play the greatest today, but I was able to kind of salvage a good round and had a good break on eight," Mickelson, who also recorded two birdies and three bogeys, told reporters. "That was kind of a nice little bonus.

"I left myself uphill par putts on seven and nine, and that's really not a good thing to do here. If you're going to make five or six-footers, you really have to have them uphill where you can hit them aggressive enough to hold the line.

"They just kind of wobbled off, so I ended up missing those," added the four-times major champion, who totalled 25 putts while hitting only eight of 18 greens in regulation.


"So with 36 holes to go I'm right in the thick of it. I've got to go out and shoot some low scores because they're out there, but I gave myself a good opportunity."

Pettersson, who like Mickelson started his round at the 10th, briefly moved into a tie for the lead at six under before bogeying two of his last five holes.

"I played pretty good," the Swede said after a round that also included three early birdies. "I made a couple stupid bogeys coming in, but overall I'm hitting it great. I'm looking forward to the weekend."

British world number one Luke Donald, who opened with a 70 in the strong gusts of Thursday, was among the late starters in the second round.

The cut was projected to fall at two-over 144 with Spaniard Sergio Garcia, Australian Geoff Ogilvy and 2006 champion Rory Sabbatini of South Africa among those in danger of missing out.

(Editing by Frank Pingue)