Coach Tom Cable made the announcement of the change following practice as the Raiders (2-7) prepare to play the Cincinnati Bengals on Sunday. Cable said this was not a temporary move, that his plan is to stick with Gradkowski.
"I don't want to be like that," he said. "This is where we're headed and what we're going to do. He'll take this team and go with it."
Russell was not in the locker room during the media access period and was not available for comment after the decision was announced. Cable said Russell was disappointed by the decision but worked hard in practice Wednesday.
Cable said owner Al Davis gave him the autonomy to make the decision on his own and supported the move.
"As we all know, it's important to include him in everything so he knows what's going on with this football team," Cable said.
Cable had pulled Russell for ineffectiveness in two of the past three games as he grew more frustrated with Russell's inaccuracy and poor decision-making in his third season in the NFL.
The Raiders believed Russell would be the quarterback to turn the struggling franchise around when they drafted him No. 1 out of LSU in 2007 and eventually gave him a contract with about $31 million in guaranteed money. But his career has sputtered from the start.
He had a lengthy holdout as a rookie before finally signing his deal after the first game of the season. He played briefly down the stretch before getting the starting job a year ago. Russell was inconsistent in his first full season as a starter, but showed some bright signs with a strong finish to the season that included wins over Houston and Tampa Bay.
Instead of having a breakthrough in his third season, Russell has regressed and has been booed regularly at home games. He has completed just 46.8 percent of his passes this season, with nine interceptions and five lost fumbles and the second worst passer rating in the league at 47.7.
Cable said he still believes in Russell's future even if all signs appear to be pointing to him becoming one of the more notable draft busts. Russell will be the No. 2 quarterback this week against the Bengals.
"This is in no way giving up on the guy," Cable said. "This is just trying to jump-start this team and really break it down and make a decision based on what gives us the best chance to win."
In 28 career games, Russell has completed 51.6 percent of his passes with 17 touchdowns, 21 interceptions and 14 lost fumbles for a passer rating of 65.5. He had started 25 of the past 26 games for Oakland, missing only one last year with an injury.
The Raiders used top 10 picks the past two seasons to surround Russell with speedy playmakers, drafting running back Darren McFadden and receiver Darrius Heyward-Bey. But Oakland has been unable to generate a big-play offense, scoring just 88 points in the first nine games.
Russell has particularly struggled on the deep passes he was supposed to be so proficient with because of his big arm. According to STATS LLC, Russell has completed just 2 of 34 passes that have gone more than 20 yards downfield for 85 yards, one touchdown and five interceptions.
"We've got guys open, and I think we're getting better in understanding what we're doing," Cable said. "We've got to put the ball in their hands and find a way to do that. I think this will give us an opportunity to do that."
This will be just the second start for Gradkowski since 2006. He started one game last year in Cleveland, going 5-for-16 for 18 yards and two interceptions for a passer rating of 1.0 in a 31-0 loss to Pittsburgh. He started 11 games as a rookie for Tampa Bay in 2006, winning three of them.
Gradkowski is 17 for 30 for 163 yards and two interceptions as a backup in Oakland this season. He tried to lead a comeback last week against Kansas City before his pass in the final minute deflected off receiver Heyward-Bey's hands and knees before being intercepted by Mike Brown around the 10-yard line to seal a 16-10 win for the Chiefs.
"I thought last week there were some good things and definitely some things to learn from," Gradkowski said before the decision was announced. "All we can do is keep working and get better."
Gradkowski got limited practice time with the first team for most of the season as the Raiders worked on developing Russell. He got a few more chances last week and now will get the bulk of the time with the first team. He expects that to be a big help this week against the Bengals.