The Packers listed Fisher as questionable, meaning there is a 50-50 chance of playing, Friday on their injury report. Instead of practicing Friday, Fisher underwent a magnetic resonance imaging test to further determine the soreness he has felt just below his shoulder blade area all week.
Fisher practiced Wednesday and Thursday, but the soreness has lingered and he was held out of practice. Fisher said he likely was hit in that area during Green Bay's loss to Cincinnati last Sunday.
"It's just part of the game," Fisher said. "It didn't stop me from playing in the game. I don't even know when it happened (against Cincinnati). It didn't stop me from practicing on Wednesday. I was taking hits in practice (Thursday)."
Fisher said that X-rays showed no bone fracture. The MRI will give Fisher and team doctors a closer, detailed look at the area of pain.
Fisher has moved from third-string to starter due to season-ending injuries to Ahman Green and Najeh Davenport. He rushed for 51 yards on 17 carries (3.0 avg.) against the Bengals in his first career start.
Though he is listed as questionable, Fisher is determined to play against Pittsburgh unless the MRI and team doctors refuse to let him suit up.
"With certain rib injuries, you don't want to risk having a punctured lung, or something like that," Fisher said. "That's a worse-case scenario. I don't expect it to be that serious. I expect to be out there playing."
If Fisher is unable to play, Coach Mike Sherman said Rashard Lee will start and be backed up by Walter Williams and Samkon Gado. Fisher's absence would be a setback for the Packers, especially in the passing game because of his awareness of blitzes and how to protect Brett Favre. Williams will be the third-down back if Fisher is sidelined, Sherman said on Friday.
"(Williams) has done that all week," Sherman said. "We've schooled him up in that area specifically so he'd be a guy we could use and feel comfortable with on third down in protection."
Fisher feels the coaches won't have to refer to Plan B against the Steelers.
"I'm not passing up no opportunities," Fisher said. "I've worked too hard to be in the position I'm in. ... We already got enough stuff going on with the team right now. I'm not going to create another problem."
Diggs has been recovering from a sprained knee that he sustained Oct. 3 against Carolina. He has practiced this week, but probably won't return until Green Bay's game Nov. 13 at Atlanta.
Ferguson sprained his left knee Oct. 23 against Minnesota. He hasn't practiced all week. He could be out another one to two weeks.
Martin hasn't practiced this week, either. He is expected to miss his second straight game with a groin injury. He sustained a similar injury during training camp, but his current injury is to a different area, according to Sherman.