FOXBOROUGH, Mass. — The San Diego Chargers like what they're hearing from Philip Rivers.

Forced to leave last weekend's upset win because of a sprained right knee, the mouthy quarterback is "optimistic" about playing Sunday in the AFC championship against the New England Patriots.

Rivers returned to the practice field Friday for the first time this week and sounded ready to go.

"I think honestly, given the magnitude of the game and given the situation, if I'm out there, as I plan to be for the first snap and throughout the game, it won't have an effect at all," he said.

Chargers coach Norv Turner is taking a more cautious approach. He listed Rivers as doubtful and said it would be a gametime decision.

"We want him to be able to move well enough to protect himself," Turner said.

Already a two-touchdown underdog against the perfect Patriots, the Chargers are awfully banged up. Star running back LaDainian Tomlinson said he thought his hyperextended left knee would be OK for him to start, but tight end Antonio Gates was put in the doubtful category.

Patriots coach Bill Belichick said San Diego's injury problems were of little concern to him.

"We get ready for all 53 players every week," he said. "We don't have any control over that."