Already reeling from the loss of impact rookie Phillip Buchanon, the Raiders now have to deal with the news that Charles Woodson will be unable to return this weekend for Oakland's game at Kansas City.

Woodson initially was listed as questionable for the game against the Chiefs, but ESPN.com's John Clayton confirmed the cornerback will not play Sunday. A report in the Contra Costa Times had said the cornerback took a step backward at Thursday's practice.

Woodson, recovering from a broken right shoulder, did not practice in pads with the team. A day earlier, he had practiced at full speed for the first time since suffering the injury on Sept. 15.

According to coach Bill Callahan, Woodson and the trainers decided to "back him down" as his shoulder showed signs of weakness, the newspaper reported.

"He's progressing, showing signs he can get back in the lineup," Callahan said. "Some days it's weaker and a little sore. Some days it's stronger."

Woodson has missed the last four games, and the effects are clear to the Raiders. They now have the 27th-ranked defense in terms of passing yards given up, surrendering an average of 242.5 passing yards per game.

Callahan said cornerback Terrance Shaw will start in Woodson's absence.