"Twelve Raiders have gone down with hamstring injuries since the start of training camp (13 if you count Darren McFadden twice), and guard Robert Gallery chuckled Thursday when he was asked for a possible explanation.

"It's hard to say," Gallery said. "The doctors say it's from overwork, so I guess I will go with what the doctors say."

Gallery's hamstring popped in the season opener against Tennessee, and he returned to practice this week. He said he is good to go and will return to the starting lineup Sunday against the 49ers at Candlestick Park.

McFadden's left hamstring tightened up during training camp and he missed three weeks. Now, it's his right one and while it's not as bad - the running back returned to practice in limited fashion Wednesday - he is not sure if he can play Sunday.

"Right now, I'm still feeling it," McFadden said. "I haven't just gone out there and tried to go 100 percent all the way."

McFadden, who ran for 392 yards and caught for 162 in the first four games, missed Sunday's win over San Diego and said he is 50/50 to play against the Niners. He is having a hard time not thinking about re-injuring the hamstring.

"I am taking my time with it," McFadden said. "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."

As for Gallery, he had no illusions of returning before he could get in a stance and drive, and that just happened a few days ago."