Starter Josh McCown pulled up a little lame on his injured right foot Friday, so after Friday's practice, Raiders coach Lane Kiffin all but declared Culpepper the starter for Sunday's game at the Denver.
Culpepper handled a good portion of Friday's practice while McCown was officially listed as doubtful. Kiffin said he would look to see how McCown can move on the foot Saturday, but Culpepper now appears to have secured the starting job.
Earlier in the week, Kiffen had said McCown would start if he were healthy, but he's been slowed by his foot injury as well as a right index finger problem.
McCown started the season opener against Detroit, and was 30-for-40 for 313 yards, two touchdowns and two interceptions. He held off Culpepper, who signed with Oakland after being released by Miami on July 17, for the starting job.
McCown got the starting nod mostly because McCown knew the offense better because he joined the team three months earlier than Culpepper. McCown also does a better job protecting the football, an important attribute because Kiffin had stressed in the preseason that he would rely heavily on his defense.
Culpepper has more big-play ability, 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.
Culpepper blew out his knee in 2005 with the Vikings and began 2006 as Miami's starter, but had trouble with his mobility and was sacked 21 times in the first four games. The Dolphins shut him down so he could continue rehabilitation and eventually placed him on injured reserve. When Miami acquired Trent Green in a trade with Kansas City this offseason, Culpepper became expendable.
In eight NFL seasons, Culpepper has passed for 21,091 yards and 137 touchdowns with 89 interceptions. He has a career quarterback rating of 90.8.
ESPN.com senior writer John Clayton and The Associated Press contributed to this report.