Crabtree was previously deemed questionable with a chest injury.
The wide receiver was a limited participant in Wednesday's and Thursday's practice sessions, but sat out Friday.
Crabtree suffered the injury during Sunday's loss to the Washington Redskins, after getting leveled in the open field during the fourth quarter.
If Crabtree is ruled out, expect Seth Roberts to see more targets in the passing game.
It's a difficult development for the Raiders, who sport an identical 2-1 record to the Broncos, in what is expected to be a pivotal divisional game.
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