San Diego Chargers running back Ryan Mathews leaves the San Francisco 49ers' defense behind him as he scampers for a 54-yard touchdown during the first quarter of an NFL preseason football game Thursday, Sept. 1, 2011 in San Diego. (AP Photo/Denis Poroy)

San Francisco 49ers running back Kendall Hunter leaves San Diego Chargers defensive back Traye Simmons on the ground while gaining 17 yards on a run during the first quarter of an NFL preseason football game Thursday, Sept. 1, 2011 in San Diego. (AP Photo/Gregory Bull)

San Francisco 49ers running back Kendall Hunter is turned up side down by San Diego Chargers defensive back Bob Sanders after a 5-yard gain during the first quarter of an NFL preseason football game Thursday, Sept. 1, 2011, in San Diego. (AP Photo/Denis Poroy)

San Francisco 49ers quarterback Alex Smith goers into a slide to avoid the hit by San Diego Chargers defensive back Eric Weddle during the first quarter of an NFL preseason football game Thursday, Sept. 1, 2011, in San Diego. (AP Photo/Denis Poroy)

San Diego Chargers defensive end Corey Liuget runs over San Francisco 49ers quarterback Colin Kaepernick while collecting a sack in the second half of a NFL preseason football game Thursday, Sept. 1, 2011 in San Diego. (AP Photo/Denis Poroy)

San Diego Chargers wide receiver Laurent Robinson, left, hauls in a pass as San Francisco 49ers defensive back Chris Culliver defends in the second half of their preseason NFL football game Thursday, Sept. 1, 2011, in San Diego. (AP Photo/Gregory Bull)

San Francisco 49ers quarterback Colin Kaepernick scrambles during the second half first of a NFL preseason football game against the San Diego Chargers Thursday, Sept. 1, 2011 in San Diego. (AP Photo/Denis Poroy)

San Diego Chargers quarterback Scott Tolzien has the ball knocked from his hand by San Francisco 49ers linebacker Aldon Smith during the second quarter of a NFL preseason football game Thursday, Sept. 1, 2011 in San Diego. (AP Photo/Denis Poroy)

San Diego Chargers wide receiver Seyi Ajirotutu, right, runs with the ball as San Francisco 49ers defensive back Tramaine Brock tackles him in the first half of their preseason NFL football game Thursday, Sept. 1, 2011, in San Diego. (AP Photo/Gregory Bull)

San Diego Chargers defensive back Marcus Gilchrist, right, and linebacker Donald Butler tackle San Francisco 49ers wide receiver Kyle Williams after a short gain on a pass play during the second quarter of a NFL preseason football game Thursday, Sept. 1, 2011 in San Diego. (AP Photo/Gregory Bull)

San Francisco 49ers running back Anthony Dixon follows fullback Moran Norris into the line during a NFL preseason football game Thursday, Sept. 1, 2011 in San Diego. (AP Photo/Denis Poroy)

San Francisco 49ers Chase Beeler (61) and Ian Williams (64) sack San Diego Chargers quarterback Scott Tolzien (16) during the fourth quarter of a preseason NFL football game Thursday, Sept. 1, 2011 in San Diego. The 49ers won 20-17. (AP Photo/Denis Poroy)

San Francisco 49ers defensive back Chris Culliver (29) intercepts a pass in front of San Diego Chargers wide receiver Seyi Ajirotutu (89) during the fourth quarter of a preseason NFL football game Thursday, Sept. 1, 2011 in San Diego. The 49ers won 20-17. (AP Photo/Denis Poroy)

San Diego Chargers quarterback Philip Rivers warms up prior to the Chargers' NFL preseason football game against the San Francisco 49ers on Thursday, Sept. 1, 2011, in San Diego. (AP Photo/Denis Poroy)

San Francisco 49ers quarterback Alex Smith fires a pass against the San Diego Chargers during the first quarter of an NFL preseason football game Thursday, Sept. 1, 2011, in San Diego. (AP Photo/Denis Poroy)

San Francisco 49ers running back Kendall Hunter is drilled by San Diego Chargers defensive end Jacques Cesaire after a short gain during the first quarter of an NFL preseason football game Thursday, Sept. 1, 2011 in San Diego. (AP Photo/Denis Poroy)

San Francisco 49ers wide receiver Ted Ginn is tackled by San Diego Chargers defensive back Quentin Jammer after catching a pass for a 5-yard gain\ during the first quarter of an NFL preseason football game Thursday, Sept. 1, 2011 in San Diego. (AP Photo/Denis Poroy)

San Francisco 49ers quarterback Alex Smith rolls out during the first quarter of a NFL preseason football game against the San Diego Chargers on Thursday, Sept. 1, 2011, in San Diego. (AP Photo/Lenny Ignelzi)

San Francisco 49ers wide receiver Josh Morgan is driven out of bounds by San Diego Chargers defensive back Antoine Cason just before the end zone in the first quarter of an NFL preseason football game Thursday, Sept. 1, 2011, in San Diego. (AP Photo/Denis Poroy)