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Stefen Wisniewski walked slowly through the Raiders locker room, a thick black brace around his right knee. He paused at his stall briefly, donned a black hoodie then shuffled back out the way he came.

For only the second time in three seasons, Oakland's starting center is facing a Sunday with no football. Wisniewski suffered a knee sprain in last week's loss to the Washington Redskins and hasn't practiced since.

It's another blow to the Raiders offensive line, which could go into Sunday's game against San Diego with only one of its projected starters still in place.

Since losing left tackle Jared Veldheer to a triceps injury in training camp, Oakland has scrambled to keep the same unit on the field for longer than a week.