updated 3:59 p.m. ET Sept. 30, 2008

PITTSBURGH - The Pittsburgh Steelers haven’t been this thin at running back since losing 1,000-yard rushers Franco Harris and Rocky Bleier to injuries before the 1976 AFC championship game.

With Willie Parker and Rashard Mendenhall injured and out, the division-leading Steelers are down to one healthy running back for Sunday night’s key AFC game in Jacksonville — Mewelde Moore, who had only one carry in their first three games.

Parker, coming off three consecutive seasons with 1,200 or more yards, will miss his second straight game with a strained knee. It still isn’t certain if Parker will be ready for the Oct. 19 game at Cincinnati, which follows an off week.

“We live week to week and day to day,” coach Mike Tomlin said Tuesday, barely 12 hours after a 23-20 overtime victory over AFC North rival Baltimore. “We’re going to Jacksonville this weekend and we need somebody to tote the thing.”

The injuries may force the Steelers (3-1) to sign two running backs — an unusual move at this stage of a season. Former backup Najeh Davenport may return and Gary Russell, a former University of Minnesota back who spent the 2007 season with them, could be promoted off the practice squad.

Carey Davis, the fullback, also has a sprained ankle and may not play Sunday night.

“Rest assured we will play with a running back this week,” Tomlin said.

Parker’s injury gave first-round draft pick Mendenhall a chance to make a major contribution as a rookie, but he needs surgery for a fractured right shoulder and will miss the rest of the season. He was hurt while being hit by Ravens linebacker Ray Lewis during Mendenhall’s first career start.

Right guard Kendall Simmons also ruptured an Achilles’ tendon on Monday and won’t play again this season. Even before Mendenhall and Simmons were hurt, the Steelers were without Pro Bowl nose tackle Casey Hampton (groin) and defensive end Brett Keisel (calf).

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Neither Hampton nor Keisel will play at Jacksonville (2-2) and Keisel is expected to miss at least a couple of more games.

Darnell Stapleton replaced Simmons against Baltimore but the more-experienced Trai Essex could start Sunday. Another option is to move right tackle Willie Colon to guard and put former starter Max Starks back at tackle.

Davenport was let go after gaining only 52 yards in two starts following Parker’s season-ending broken right leg Dec. 20 in St. Louis. The Steelers’ inability to run effectively without Parker during their 31-29 wild-card playoff loss to Jacksonville led them to draft Mendenhall in April.

Because the Steelers have a short turnaround after the Monday night game, it is unlikely that either of the two pickups would be ready to start. That means Moore, normally the third-down back, is likely to also get carries on first and second downs.

Moore ran for 62 yards and a 4.3 average while starting eight games for Minnesota in 2005. He has a 4.8 average on 273 carries during his career, but has only nine rushing attempts this season. He ran eight times for 13 yards against Baltimore.

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Despite that limited production, Moore made one of the Steelers’ biggest plays in overtime, a 24-yard gain on a swing pass that led to Jeff Reed’s game-winning 46-yard field goal.

“If he was frustrated in any way, he didn’t show it,” Tomlin said of Moore’s limited role before Monday. “He delivered some plays for us at critical times. He can win some one-on-one matchups with linebackers. Hopefully, it’s a big step in where we’re headed with him.”

Still, the Steelers’ injury situation is reminiscent of that 24-7 loss to Oakland 32 years ago, when Reggie Harrison — mostly a special teams player — was their only healthy back going into the AFC title game.

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With no running game for quarterback Terry Bradshaw to lean on, the Raiders forced numerous mistakes that ended the Steelers’ 10-game winning streak and their run at a third consecutive Super Bowl.

“Injuries always happen at a bad time,” Tomlin said, repeating former coach Chuck Noll’s message at the time. “They’re part of the game. I’m not going to complain about them and go ‘Woe is me.’ They’re as much a part of the game as blocking and tackling.”

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