Heading into Sunday's game against San Diego, Wakefield knows he could be counted on heavily as a defensive lineman trying to tackle LaDainian Tomlinson because starting defensive tackle Gerard Warren could be out with a pectoral injury.

"It's like they say: Jack of all trades, but master of none," Wakefield said Wednesday. "I get to the point where I can compete and play and make some plays, but at the same time you never get a chance to sit at one spot and hone in on what you need to do. It's kind of a double-edged sword. But hey, I get to play. It's much better than sitting and watching everybody else.

Wakefield signed with the Raiders in 2007 as a blocking tight end and missed his first season with a knee injury. He worked at both tight end and defensive line in offseason workouts, but moved to defensive line when training camp started. An injury to Marc Wilson early in camp led to Wakefield being moved back to the offensive line, where he stayed until the end of the preseason.

He moved back to defensive line, where he played at for his first three NFL season, at the end of the preseason and played only briefly until Warren left last week's game at Buffalo with the injury early in the fourth quarter.

"It's getting better," Wakefield said. "Most of my reps over the last few weeks have been at end. But he had me practice individual and practices here and there at tackle so it helped. When I move somewhere, it's a matter of getting the reps, getting used to it and rolling with it."

Warren was one of many key Raiders to miss practice Monday, including running backs Justin Fargas (groin) and Darren McFadden (turf toe), defensive end Derrick Burgess (triceps), cornerbacks Nnamdi Asomugha (foot) and Stanford Routt (ankle), and offensive lineman Cooper Carlisle (ankle).

The most serious injuries are to Warren, Carlisle and Fargas, who could all miss this week's game against the Chargers. But coach Lane Kiffin said he expected the other players to return to practice Thursday and those three to be healthy when Oakland returns from the bye week Oct. 12 against New Orleans.

Warren's injury last week played a key role in the Raiders late-game collapse against the Bills. He got hurt in the second quarter but remained in the game until early in the fourth. He finally had to come out when the pain became too much and the Bills rallied to score 17 points in the final quarter, overcoming a nine-point deficit to win 24-23.

With Wakefield and run-stuffer Terdell Sands sharing time at tackle next to Tommy Kelly in the final minutes, the Raiders struggled to generate a consistent pass rush against Trent Edwards.

Now Oakland may need to go an entire game with those two against the team that has scored the second most points in the NFL through three weeks.

"This will be a big test for Fred, going against a really good offensive line," Kiffin said. "Fred's doing well. It's not an easy thing to do. The guy was playing offensive line the third week of preseason and he goes over to defensive line. Not just defensive end, he's inside at defensive tackle. That's a very, very hard thing to do. That doesn't happen very often in the NFL for a guy to just flop over there. So Fred's doing his best."

Notes: If Carlisle can't play Sunday, Chris Morris is expected to start in his place. ... McFadden and Michael Bush would split time at running back again in place of Fargas. ... The Raiders did get one positive piece of news on the injury front when starting left tackle Kwame Harris returned to practice after missing the previous two games with a knee injury.