"Preseason games don't count, but sometimes do they matter. The Raiders couldn't stop the run against the 49ers on Saturday night, and more important, they lost quarterback Jason Campbell late in the first half.

Campbell was knocked out of the game with 2:44 left in the second quarter, after taking a knee to the helmet. He said he was dizzy, didn't return in the 17-3 loss at Candlestick Park and will get tested for a concussion in the coming days.

"I'm just glad I'm all right," Campbell said. "We'll see how the tests go and what the trainers say, and take it from there."

Campbell took some big shots last season and had three stingers - injuries that affect the nerves in the neck and shoulder region - but said this felt totally different.

On Saturday night, Campbell was trying to escape pressure when he fumbled the ball. As he was reaching down for it, he took a hard hit from linebacker Ahmad Brooks near his left shoulder. He remained on the turf for a couple of minutes before slowly walking off the field.

Trent Edwards came in and would throw an ugly interception into double coverage at the San Francisco 20 with 47 seconds left in the half. The fact that Kyle Boller came in at quarterback to start the third quarter was a coincidence, Raiders coach Hue Jackson said. The two are battling for the No. 2 job, and the plan was always to have Boller play the second half.

The Raiders (0-2) were lucky to be down only 10-0 at halftime, as their first-team defense gave up 226 yards, 100 rushing on 20 carries. Linebacker Rolando McClain had an interception off a botched field-goal attempt, and defensive end Matt Shaughnessy also had an unlikely pick. He dropped back in coverage on a zone blitz, and Alex Smith never saw him when he threw for Vernon Davis with nine seconds left in the first quarter.

Still, Jackson wasn't in any mood to look on the bright side."