NASHVILLE, Tenn. -- In a mild surprise, San Francisco 49ers nose tackle Glenn Dorsey is active and he will start Sunday at Tennessee.Dorsey missed practice on Wednesday and Thursday. He was listed as questionable on the injury report. Dorsey injured his right hamstring in the first quarter of last Sunday's win over Arizona.Rookie Quinton Dial, activated from the physically unable to perform list Saturday, is active.Running back LaMichael James is inactive again.