THOUSAND OAKS, Calif. -- When Graeme McDowell gets hot with his putter, he can be tough to beat.
The former U.S. Open champion from Northern Ireland seems very comfortable with his flatstick this week at the World Challenge presented by Northwestern Mutual at Sherwood Country Club.
He fired a 6-under-par 66 -- the low round of the week -- in damp conditions Friday, fashioning seven birdies and only one bogey. His 36-hole total of 9-under 135 is three strokes better than that of Bo Van Pelt (68), Jim Furyk (69) and Keegan Bradley (69).
Defending champion and tournament host Tiger Woods, a five-time winner of the event, shot 69 and is alone in fifth place, four strokes back at 5-under 139.
"Just kind of fairways and greens," said the recently engaged McDowell. "I actually putted a little better today. To be honest, I have been pretty cold with my putting all year."
McDowell finished second at Sherwood in 2009, then beat Woods on the first hole of a sudden-death playoff in 2010, holing a 20-foot birdie putt on the 18th green after both players had birdied the final hole in regulation.
"This golf course has some good memories for me," McDowell said.
McDowell got off to a blazing start Friday by posting three straight birdies. He logged his only bogey of the day at the par-4 seventh and made the turn in 2-under 34.
On the back nine, McDowell birdied Nos. 10, 13, 16 and 17 to finish with a 4-under 32.
Over two days, McDowell has carded 11 birdies and only two bogeys.
"You can just take dead-aim on these greens," he said, alluding to the rain-softened surfaces.
For the second consecutive day, players were allowed to use preferred lies. McDowell expects someone to go low on the weekend.
"There's always a score to be had out there," he said.
Third-round play will be held Saturday, with the final round set for Sunday. The winner will receive $1 million.
McDowell and Van Pelt will tee off Saturday at 10:58 a.m. local time in the last twosome of this elite 18-player field.
Proceeds benefit the Tiger Woods Foundation.