Cornerback Chris McAlister and defensive tackle Haloti Ngata have taken part in practice, but it appears both starters have been limited by the coaching and medical staffs.

McAlister, who has not played this preseason due to a knee injury, participated in individual drills, but when the first defense took the field, Frank Walker took McAlister's spot opposite Samari Rolle.

Ngata, who has been hampered by a sprained medial collateral ligament in his right knee, has also been limited. Today, he was used as a running back for the scout team.

“The coaches have already been holding me out," Ngata said. "I tried to put myself in, but they’re still being cautious about my injury and making sure that I am 100 percent.”

Other observations:

• Players who did not practice during the portion of today's session open to the media included: cornerbacks Fabian Washington (hamstring) and Derrick Martin (right shoulder); quarterbacks Kyle Boller (right shoulder) and Troy Smith (illness); free safety Ed Reed (shoulder); running back Willis McGahee (arthroscopic knee surgery); defensive tackle Kelly Gregg (arthroscopic knee surgery); and rookie wide receiver Marcus Smith (separated right shoulder).

Boller wore sweatpants and a cap as he watched rookie Joe Flacco take all of the reps.

• Rookie linebacker Tavares Gooden (concussion) returned to practice after sitting out yesterday's session.