Chargers inside linebacker Kevin Burnett, an offseason free-agent acquisition, sustained a stinger less than five minutes into the game and didn't return.
This one was notable for which Chargers didn't play -- quarterback Philip Rivers, tight end Antonio Gates, running backs LaDainian Tomlinson and Darren Sproles, and wide receivers Vincent Jackson and Chris Chambers.
Coach Norv Turner had said Tomlinson wouldn't play. L.T. did play in the first two exhibitions, his first preseason appearances since 2005.
"It's something we may need in a game," Turner said. "It's something you've got to practice. I would hate for a critical situation to be the first time we did it in the regular season. We got a chance to work on it."
Volek didn't take a snap last season. He hasn't played in a real game since replacing the injured Rivers and scoring the winning touchdown on a 1-yard sneak in a 28-24 upset win at Indianapolis in a divisional-round playoff game in January 2008.
Osgood would like to be a receiver but has caught only four passes the last four seasons. He's better known as a special teams ace, earning two trips to the Pro Bowl.
Burnett was down for several minutes before getting up and walking off the field. He then headed to the locker room with a trainer.
San Francisco starting quarterback Shaun Hill was in for just the opening series.
"We moved the ball a little bit," Hill said. "We weren't able to get any points, but it was good to at least get out there and run some plays and get things started out there.
"I was happy that I got the opportunity and I think the whole offense felt that way," Hill said. "We think it was important to get some work tonight. We've got a long weekend off, so we were excited about it."
The 49ers open at Arizona a week from Sunday. The Chargers, aiming for their fourth straight AFC West title, open at Oakland a week from Monday night.
San Diego kicker Nate Kaeding got a good workout, with field goals of 36, 47, 51 and 28 yards.