Because of an Achilles injury, Mendenhall has missed all four games of a winning streak that the Steelers (6-3) carry into their Sunday showdown with the Baltimore Ravens (7-2).
Mendenhall had not been through a full practice in more than a month, but made it through complete workouts Wednesday, Thursday and Friday. He is officially listed as probable.
"He looks like he's back to his old form," running back Isaac Redman said. "He's making all the cuts, it looks like he has his burst. So he looks good."
With former 1,200-yard rusher Mendenhall back, the Steelers have to decide how to split carries between he, Redman and Jonathan Dwyer. Redman and Dwyer each had 100-yard rushing games while Mendenhall was out.
"All three of us are going to play," Redman said. "And we're just going to keep it rolling throughout the game and try to keep a fresh running back in there at all times. We're going to try to pound them."
With Mendenhall unavailable to play the first three games of the season because of his recovery from a torn ACL sustained Jan. 1, the Steelers running game struggled. Pittsburgh averaged 65 rushing yards per game in starting 1-2.
Since Mendenhall returned with a 68-yard performance in a win over Philadelphia Oct. 7 -- to that point, the most yards by a Pittsburgh back this season -- the Steelers have improved their NFL ranking in rushing yards from 31st to 20th.
After being deactivated for the two previous games, Dwyer had consecutive 100-yard efforts in victories over Cincinnati and Washington. Then Redman had 147 rushing yards in a 24-20 win at the defending Super Bowl-champion Giants Nov. 4.
"We were able to get those 100-yard games and able to kind of pound teams out," Redman said, "and kind of make them quit in the fourth quarter."
After a mediocre, Dwyer-led, 95-yard rushing performance in a lackluster 16-13 overtime win over the last-place Kansas City Chiefs on Monday, the Steelers will have the choice of three feature backs when first place is on the line Sunday.
"We're ready, and we have all three guys -- the first time all three of us are going to suit up at the same time," Redman said. "So we're really looking forward to this running game."
Whether on marching orders from the coaching staff or simply because even they aren't aware of coordinator Todd Haley's intentions, the backs insist they don't know the plan for sharing carries. Counting fullback Will Johnson, rookie speedster Chris Rainey and special teams stalwart Baron Batch, it's likely the Steelers will dress six running backs against the Ravens.
"Good thing I'm not the offensive coordinator," Mendenhall said with a smile. "For us, our focus is winning first and foremost, and we want to do well as an offense with whatever helps us to do that. It's a long season, and we're going to need everybody."
Dwyer and Redman have been steadfast in maintaining that, when healthy, Mendenhall -- a 2008 first-round pick -- is the first-team back. A free agent after the season, Mendenhall said he feels 100 percent healthy.
"I wouldn't step out there if that wasn't the case," he said. "I feel good with where I'm at."
With quarterback Ben Roethlisberger out with his shoulder and rib injuries, Pittsburgh will lean on the run game against a Ravens defense that ranks 26th in the league in rushing yards allowed. Pittsburgh's Byron Leftwich is making his first NFL start at quarterback in more than three years.
"If (yardage) comes in chunks, if it comes in dink-and-dunk, it doesn't matter," Leftwich said. "We don't care. We're just trying to win the football game. "We all understand the importance of this football game. Let's not try to act like it ain't. This is an important football game for both teams."
Roethlisberger isn't the only prominent Steelers player ruled out of Sunday's game. Receiver Antonio Brown (ankle) will miss his second consecutive game, All Pro safety Troy Polamalu has played only once since the season opener because of a calf injury and starting right tackle Marcus Gilbert (ankle) has missed four straight games.
Free safety Ryan Clark is probable to play six days after sustaining his second concussion in a 16-day span against the Chiefs.
"Nothing is wrong," Clark said on Friday. "No sensitivity to light, no headaches, no extra fatigue and no problems sleeping. Everything is fine. I'm good to go and excited to be out there on Sunday."