The question arises again as it did before last season: Duce Staley or Jerome Bettis? Only this time, it's not which halfback will start but which will back up Willie Parker.

The two veteran backs who shared 442 carries and 1,771 yards rushing at the position last season have no carries in three games. But for the first time this year, both Staley and Bettis are healthy, practicing and ready to play Monday night in San Diego.

But will they? Coach Bill Cowher may not have the luxury to dress all four of his halfbacks for his game against the Chargers, and only Cowher knows the answer to what his plans are for them. Neither Staley nor Bettis play on special teams.

"I can do about anything," Cowher said. "We'll see how the week unfolds and go from there."

Parker led the AFC with 327 yards rushing after three games, and he has a 5.1-yard average per carry. But he lost at least five pounds off the 210 he weighed in training camp and he's coming off his worst production, 55 yards on 17 carries in a 23-20 loss to New England.

That did not warrant a demotion, but Staley and/or Bettis could eat into his playing time in San Diego. Verron Haynes, who has two catches and 64 yards rushing on 20 carries, is likely to remain the third-down back, although Cowher has said Staley could play the position.

"At some point we're going to need them all and I truly believe that," Cowher said. "It's just nice at this point to be able to have some of the options we may have going into this game."

Injury report

Cowher listed three players as questionable for Monday's game because of injuries: WR Hines Ward (hamstring), LB Joey Porter (knee) and CB Ike Taylor (knee). Six are probable: CB Ricardo Colclough (ankle), LB James Farrior (back), Staley (knee), Bettis (calf), WR Sean Morey (hamstring), CB Deshea Townsend (foot). LB Clark Haggans is out after groin surgery.

He's the best

San Diego halfback LaDainian Tomlinson has 450 yards rushing and eight touchdowns, caught nine passes and has thrown for a touchdown. He's the man Cowher said the Steelers have to stop Monday night.

"LaDainian Tomlinson, I think, is the best back in the game today," Cowher said. "You look at all the things he can do. You look at the fact what he can do with the ball in his hands running -- he can catch, he can throw, he's a guy who's extremely elusive, he has great balance and great vision. When you do hit him, he doesn't always go down. I think it starts right there, starts and stops with him."

Poor performance

Add Cowher to those who believe the Steelers' offensive line did not play well against New England.

"We did not play to, I think, our ability and the standard we set around here. So, you'd like to think that is something that is correctable.

"Time will tell if it is or isn't. We need to be more consistent from that perspective.

"Not to take anything away from New England, sometimes you're going to have a day like that. You look at the last game, we did not play our best game."

Linebacker shifts

James Harrison, who will start in place of Haggans, will be relieved of some of his special teams duties, but not all. Cowher said the team began working rookie inside linebacker Rian Wallace on the outside and they've also used defensive end Brett Keisel on the outside in practice in case of an emergency. Undrafted rookie Andre Frazier is the only outside linebacker left on the depth chart behind Harrison and the injured Porter.