Clinton Portis’ sprained knee showed no improvement Thursday, and the Washington Redskins running back appears unlikely to play in Sunday night’s game against the Dallas Cowboys. 
The NFL’s second-leading rusher left Redskins Park during practice, walking gingerly in a gray hooded sweatshirt and burgundy sweatpants to his Maserati.
Portis sprained his left knee in the 23-6 loss to the Pittsburgh Steelers before last week’s bye.
With Portis hurt, Ladell Betts appears set to start Sunday. Betts has missed the last three games with a sprained knee, but he was on the field in steady rain for Thursday’s practice. Shaun Alexander would start if both Portis and Betts are unable to play.
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