Campbell was taken off the field in a cart after being hurt on a sack by Travis LaBoy in the second quarter. He was down for about 5 minutes, causing worry among Raiders fans counting on big things from Campbell this season.
Campbell hurt his right wrist on the previous series in the game. He underwent an MRI on Sunday and will be evaluated again later this week.
"Usually I recover pretty fast," Campbell said after the game. "Right now there's no timetable. The thing is just to improve and continue to keep getting better. We don't know the timetable or anything, but at the same time, I haven't really missed any time before."
Campbell led Oakland to a touchdown on the opening drive for the second straight week, completing all four of his passes for 67 yards. But the Raiders did not get another first down with Campbell in the game.
The team announced that running back Michael Bush will undergo surgery on his broken left thumb Monday and could be back in time for the season opener.
Bush broke the thumb when he was hit on the hand by a helmet on his final carry Saturday night against San Francisco. Coach Tom Cable said Sunday there was a "good chance" Bush would be ready to play Sept. 12 in Tennessee and that he would likely not need a cast on the finger.
Bush led the team with 589 yards rushing last season and was expected to do even more this season now that Justin Fargas has been released. Bush and Darren McFadden will share the bulk of the running load this season, although both have now been hampered by injuries in the preseason.
"I saw a guy playing center for the first time in this league," Cable said. "You got to learn where to put his helmet a little bit more consistently. When he did, it was pretty good stuff. So, there's a lot to grow on. It was actually a pretty good effort by him."
Veldheer will work at both left tackle and center this week, where he is expected to be the backup at both positions.
Cable also gave a timeframe for receiver Chaz Schilens to return from last week's arthroscopic knee surgery, calling it a 3-to-6 week injury. That makes Schilens questionable for the season opener, which will be played 19 days after his procedure.
Defensive tackle Desmond Bryant (hyperextended elbow) and cornerback Joey Thomas (concussion) are day to day with injuries sustained Saturday. Defensive linemen Jason Richardson (knee) and Alex Daniels (hamstring) will likely not play in the exhibition finale Thursday against Seattle.
Copyright 2010 by The Associated Press