San Diego Chargers' quarterback Philip Rivers returned to the practice field Friday and remained "optimistic" his sprained right knee would heal enough for him to play in the AFC Championship Game against the New England Patriots. Chargers' Coach Norv Turner took a more cautious approach. He listed Rivers as doubtful, and said it would be a gametime decision Sunday. "We want him to be able to move well enough to protect himself," Turner said. Rivers took about one-third of the snaps in practice. He was hurt last weekend in the 28-24 playoff victory over the defending Super Bowl champion Indianapolis Colts, and backup Billy Volek led the winning touchdown drive. "The way I felt Monday morning, I didn't think I'd feel as good as I do right now," Rivers said. "Certainly, it can ease my mind a bit."