Defensive lineman Albert Haynesworth is showing signs of improvement in the Redskins' defense, head coach Mike Shanahan said on Monday.

Shanahan offered his first evaluation of Haynesworth after reviewing the film from last Thursday's preseason game against the Arizona Cardinals.

Haynesworth saw extensive action in the game. He posted four tackles in the Redskins' 20-10 loss to the Cardinals.

Just like it took time for Haynesworth to get in football shape, it is taking time for him to learn the nuances of the Redskins' 3-4 defense, Shanahan said.

"Anytime a person plays the defensive end or the nose position, it takes some time," he said. "It doesn't happen overnight. He played a lot of plays and did a good job considering he played a couple different positions – and not having the reps that some of the other players have had.

"It was work that was well-needed and he played hard."

Shanahan and defensive coordinator Jim Haslett won't say how much Haynesworth could play in the Redskins' regular season opener vs. Dallas on Sunday night.

Coaches want Haynesworth to refine technique required for the defensive scheme.

"It's not just the effort, it's the use of technique," Shanahan said. "Playing a couple of different positions, it's going to be tough...He worked hard. He made a few mistakes here and there. He's getting better."

Added Haslett: "Obviously the more he's out there, the better he gets, and the better his understanding is of the defense. That's why he played all of the reps the last couple of weeks."

Prior to this season, Haynesworth had not played in a 3-4 defense during his 8-year career.

In preseason this year, he played in all four games and posted six tackles and one sack.