Tiger Woods was still not happy with his play after a second-round 66 at the AT&T National at Congressional Country Club.

The world number one, tournament host for this PGA Tour event which benefits the Tiger Woods Foundation, followed yesterday's six-under-par 64, his lowest opening round in two years, with a four-under-par round on the par-70, 7,255-yard Blue Course in Bethesda, Maryland.

That was good enough for Woods to set a target for late-starting defending champion and first-round leader Anthony Kim to chase, but the 14-time major winner was not pleased his five-birdie, one-bogey round that started from the 10th tee and took him to 10 under par at the halfway stage.

"I didn't drive the ball as well as I did yesterday or hit my irons as crisp," Woods said.

"Either I hit it pretty close to the hole, within 10 feet, or I was missing greens. So it was a little bit of two ends today.

"It was nice to actually get a score out of it. I didn't shoot myself in the foot and had a stretch there from basically 17 through three where I didn't really hit the ball all that well but somehow was able to get through it and keep the momentum of the round going."

Woods was left hoping his second round would be the one that proved to be the struggle on the way to a winning score.

"Even the tournaments where I've gone pretty low, there's always that one day where you didn't really feel as good as the others.

"But sometimes those days you actually may score lower. It's just weird how that, today I hit the ball a little bit scratchy at times, but I putted better. I felt better with the putter today, hit a lot of good putts, easy tap-ins or I was making them.

"The game is kind of weird that way. Yesterday I didn't really miss a shot, and I shot six under, but today even though I was at four under, it could have been just a little bit lower, I guess."