Philip Rivers: No doubt I'll play

SAN DIEGO -- Chargers quarterback Philip Rivers participated in a morning walk-through but did not practice with the rest of his teammates on Wednesday in order to rest his ailing chest and back.

He also did not practice on Tuesday. However, Rivers said he fully expects to play against the San Francisco 49ers on Saturday.

"At this point in the week I think there's no doubt," he said.

San Diego's 33-year-old quarterback has been dealing with what teammate Antonio Gates termed a "very severe rib injury" in mid-November.

Rivers is known for his toughness. He's started 142 straight games, the NFL's second-longest active streak behind Eli Manning (166). He played despite a torn ACL against the New England Patriots in the 2007 AFC Championship Game.

Rivers said he doesn't like to miss practice but believes limiting his practice reps could help ensure that he can play this weekend.

"I hate not practicing," he said. "But I think at some point you have to do what's best for me and the team. And practicing today wouldn't have been beneficial to moving toward Saturday."

Chargers offensive coordinator Frank Reich acknowledged there's a delicate balance to resting a player during the week and getting him enough reps so that he can perform on game days.

"At this point of the season, practice is always important," Reich said. "But sometimes you have to use discretion and get a little rest, just to give yourself the best chance to be as strong as you can be when it really matters most."

The chest and back injuries have affected Rivers' performance. Through the first eight weeks of the season, Rivers completed 68.3 percent of his passes for 2,213 yards, 20 touchdowns and just five interceptions, posting a 109.9 passer rating. The Chargers were 5-3 in those games.

In the past six games, Rivers has completed 66.8 percent of his passes for 1,426 yards, seven touchdowns and eight interceptions, posting an 81.2 passer rating. The Chargers are 3-3 over that stretch.

Reich said if Rivers cannot play against the 49ers, he has confidence in backup quarterback Kellen Clemens. The University of Oregon product was 4-5 as a starter for the St. Louis Rams last season.

"One of the reasons we brought Kellen in here is that he was very competitive last year, thrown into a tough situation," Reich said. "He played well against some really tough defenses. He's a very smart, competitive guy."