Portis, the NFL's second-leading rusher, sprained his left knee in the 23-6 loss to the Pittsburgh Steelers before last week's bye.

With Portis ailing, Ladell Betts appears set to start Sunday. Betts has missed the last three games because of a sprained knee, but he was on the field in steady rain for Thursday's practice.

Vick plans on return

Imprisoned NFL quarterback Michael Vick expects to return to pro Football, according to his bankruptcy attorneys who laid out a plan to pay creditors based in part on his anticipated earnings.

"The Debtor has every reason to believe that upon his release, he will be reinstated into the NFL, resume his career and be able to earn a substantial living," Vick's attorneys wrote in a disclosure statement filed before a hearing in U.S. Bankruptcy Court in Norfolk, Va.

The former Atlanta Falcons star is serving a 23-month sentence in a federal penitentiary for bankrolling a dogfighting ring in rural Virginia and is scheduled to be released on July 20. Vick still faces two state felony counts -- dogfighting and animal cruelty. They carry maximum prison terms of 10 years, but under a plea deal, Vick would serve a suspended sentence and a year of probation.

Raiders' Walker out

Oakland Raiders wide receiver Javon Walker is scheduled to undergo ankle surgery and will probably miss the rest of the season.

He injured the ankle during a loss to Carolina last Sunday.