An MRI on quarterback Jason Campbell's injured left knee has revealed a sprain, and his playing status for Sunday's game against the Denver Broncos is uncertain, Raiders coach Tom Cable said Monday.

Cable first said Campbell's knee was fine, but a few minutes later the coach said "absolutely" when asked if he could envision No. 3 quarterback Kyle Boller starting against the Broncos.

How realistic that is will begin to crystallize Wednesday when Cable gets a look at regular starter Bruce Gradkowski (right shoulder) and Campbell in practice.

Gradkowski was injured during a victory over the San Diego Chargers on Oct. 10 and missed Sunday's loss to the 49ers.

Campbell was hurt in the first half against San Francisco but played all the way through. After completing five of his first seven passes, he missed on all but three of his next 14, finishing 8 of 21 for 83 yards and a 10.7 passer rating.

Boller, 29, has started 46 games during his seven-year NFL career. He last played in a regular-season game on Jan. 3 against the 49ers in a relief role for the St. Louis Rams. His last start came Dec. 6. He said he is ready as a starter or backup against the Broncos.

"I've pretty much stayed on top of it over the last six weeks," Boller said, "and that's part of your job. It doesn't matter if you're a starter, second-stringer or third-stringer. You have to always be into the game plan and doing just the same things the starter's doing. So, I don't think I'll miss a beat."

Boller, a former Cal standout, was on the inactive list for the first four games of the season but has been active for the last two. Against the 49ers, he was listed as No. 2 on the depth chart.

"You're one play away from going in now, versus maybe two," Boller said. "Anything I can do to help this team get to where we need to be, I'm all for it."

Campbell made it through the 49ers game without exhibiting any signs of being hurt severely, though at one point a team trainer examined his knee on the sideline.

Cable said he never considered bringing in Boller despite Campbell being at less than 100 percent and in the midst of the worst performance of his six-year NFL career.

Campbell and Gradkowski were unavailable for comment Monday.

  • Running back Darren McFadden (hamstring) sat out against the 49ers in part because he wasn't able to practice at full strength. "That's my goal for Wednesday, to go out there and try to see what I can do, see if I can burst," he said. McFadden was injured at the end of a 23-yard run against the Houston Texans on Oct. 3. He hasn't played since.

  • Cable said he "wouldn't be surprised" if the Raiders made a trade or two before today's deadline. He said he was unaware of any trades being discussed.

  • Backup tight end Brandon Myers suffered a concussion against the 49ers and is day to day. Defensive tackle John Henderson's right foot remains in a protective boot. He has missed the past four games since he suffered a stress fracture against the Rams.