Starting wide receiver Chaz Schilens had X-rays done on his left foot and missed both practices Friday.
He left the afternoon practice Thursday because of soreness in the foot that required two surgeries to repair the damage from a broken fifth metatarsal bone.
"There's no damage, anything like that," Raiders coach Tom Cable said. "It's sore. We're going to have to work with him to find out what his workload is, what he can and can't do. We're going to have to deal with it, probably from here on out."
Cable said Schilens will be limited to one practice per day until he reaches the point where he isn't at risk of aggravating the injury.
Schilens missed the first eight games last season while recovering from his first surgery in August. Doctors performed a second surgery soon after the season ended.
"I'm just finding out what I can do day-to-day and going from there," Schilens said. "Once I find that out, I'll be good to go. "... It's not that great, but we can manage it."
Cable said he's confident Schilens will make a full recovery and be the No. 1 receiver the Raiders envision.
"It's important for our team," Cable said. "It gives us another weapon who has done enough to kind of prove to us that he brings a lot to the table."
As always, Gradkowski is putting a positive spin on the situation.
"You could take it two ways," he said. "I feel like I would be the best backup, but I also feel like I'd be the best starter. You have that confidence, and, whatever my role is, I know I'm going to be ready to play. We did it last year, and I'm going to do it again."
The Raiders traded for Campbell in April and handed him the starting job. Gradkowski missed all of the offseason workouts because of a torn pectoral muscle he suffered in March.
He said it's frustrating knowing he missed so much time to stake his claim to the starting vacancy created by the release of JaMarcus Russell in May.
"It's tough because I've had no control over this past how many months "... ," he said. "I've had to sit in the background and watch everything go down. It's frustrating, but I don't forget, and I don't think the players forget, what we did last year. That was exciting."