McCown sprained his right foot in the first half of the season opener against Detroit last Sunday and missed practice Wednesday because of the injury. He was able to practice yesterday, but was sore when he arrived at the team's facility today and could not finish practice. McCown is listed as doubtful.

"We're going to have to see when he wakes up tomorrow," coach Lane Kiffin said. "I'm anticipating Daunte starting for us. We'll go day-to-day with it."

McCown got the nod in the opener based on his better knowledge of the offense and went 30-for-40 for 313 yards and two touchdowns in a 36-21 loss to the Lions. He also threw two interceptions and fumbled late in the game to kill the Raiders' attempt at a comeback.

Culpepper, who signed with the team July 31, started four games for Miami last season before being sidelined with a knee injury. Culpepper is a former Pro Bowler, throwing 39 TD passes in 2004 when he was in Minnesota.

He has been slowed by knee injuries the past two seasons, when he has committed 18 turnovers while throwing only 18 TD passes.

Right guard Robert Gallery also left practice early with a hamstring injury and is questionable for Sunday's game against the Broncos. Paul McQuistan, who started six games as a rookie last year, would be Gallery's likely replacement.