Wide receiver Santonio Holmes also was held out of practice and will be deactivated Sunday after city police stopped his car and smelled burning marijuana Thursday. Holmes, a former first-round draft pick, will be charged with a marijuana-related misdemeanor count.
"His situation has created somewhat of a distraction and we want to minimize that as much as we can and remain focused," coach Mike Tomlin said Friday.
Parker has missed three games with a sprained medial collateral ligament, but practiced earlier in the week and was expected to be ready for the matchup of teams with 5-1 records. He is listed as doubtful.
Parker would be replaced by Mewelde Moore, who began the season as the third-down back, but has rushed for 219 yards in the last two games. Moore gained 120 yards and scored three touchdowns, one on a pass reception, during a 38-10 win in Cincinnati last Sunday.
Until he was in the lineup in Jacksonville on Oct. 5, Moore had not started since 2005 when he was with Minnesota.
Two other Steelers starters also didn't practice Friday: left tackle Marvel Smith, who will miss a second successive game because of back spasms, and defensive end Aaron Smith.
Copyright 2008 by The Associated Press