ALAMEDA, Calif. -- Oakland Raiders quarterback Bruce Gradkowski missed practice for a second straight day Thursday with an injured shoulder and running back Darren McFadden said he is questionable for Sunday's game against the San Francisco 49ers with a hamstring injury.
Gradkowski was knocked out last week after taking a hard hit on his shoulder from San Diego's Shaun Phillips. He has only been able to watch practice this week and third-stringer Kyle Boller has been taking extra snaps in practice in case he needs to be the backup to Jason Campbell on Sunday.
"There's some improvement with Bruce, but unless he could work tomorrow, then we kind of know where we're headed with it," coach Tom Cable said.
Cable said if Gradkowski is healthy enough to play he would likely be the starter on Sunday for the Raiders.
McFadden will be the backup to Michael Bush if he is able to play. McFadden has practiced this week but said he is not yet 100 percent. Cable said he will not use McFadden if he's not fully healed.
"I just think that if they're tentative, they can't cut it loose," Cable said. "And if you can't cut it loose, you're not going to run hard or at the best of your ability. And if you do try to, you'll probably pull it again."
McFadden injured his right hamstring on a run in the fourth quarter two weeks ago against Houston and missed last week's game against the Chargers.
McFadden also missed a couple of weeks in training camp with a left hamstring injury and does not want to rush back too soon out of fear of making this injury even worse.
"You just try to tell yourself you just want to go out and try to coast, don't hit a burst until you feel like you can all the way," he said.
McFadden got off to a fast start this season, rushing for 345 yards in the first three games of the season as he finally started to show signs of why he was drafted fourth overall in 2008. He has 454 yards from scrimmage in his first four games and scored two touchdowns.
Bush, who missed the first two games with a broken left thumb, has picked up where McFadden left off. He had a strong fourth quarter after McFadden's injury two weeks ago against Houston and then rushed for 104 yards and the go-ahead touchdown in the fourth quarter against San Diego.
The Raiders are looking forward to having both backs healthy in the same game. That could create matchup problems when Oakland uses both on the field at the same time.
"We're going to play to their strengths," offensive coordinator Hue Jackson said. "The key in that situation is let them play. I think they both know and understand that whoever has the hot hand, they're going to get the ball. That's just the bottom line. There's no egos there, which is fun for me."
The Raiders are expected to get starting left guard Robert Gallery back for the first time since he injured his hamstring in the season opener against Tennessee.
Oakland has had a run of hamstring injuries this season but Gallery's was one of the more severe as his popped while he was chasing after an interception against the Titans.
"Until this week, I wasn't able to drive out of a stance," he said. "You can't fight through that. I just have to be comfortable with the stuff I do in practice and go in a game and do that. Obviously, it's probably not going to feel great or 100 percent -- nobody is -- but if I can go, that's what I am going to do."