PITTSBURGH—Le'Veon Bell knows it could have been worse.

The Pittsburgh Steelers rookie running back considers himself "lucky" he sustained nothing worse than a concussion after taking a big hit from Baltimore defensive back Jimmy Smith at the goal line of Thursday's 22-20 loss to the Ravens.

Bell was attempting to bring Pittsburgh within a 2-point conversion late in the fourth quarter when he crashed into Smith. The collision jarred Bell's helmet loose. By rule, the play was ruled dead immediately, nullifying an apparent touchdown.

Turns out, not scoring was the least of Bell's worries. He acknowledged Monday he was "out of it a little bit" as trainers took him off the field and wasn't aware the touchdown was negated until much later. Pittsburgh scored on the following play but couldn't execute the 2-point conversion, falling to 5-7 with a month left in the regular season.

Bell was able to run on Monday but held out of full practice. He has taken the ImPACT test under NFL guidelines and it's unclear if he'll be available for Sunday's game against Miami (6-6).

Having 10 days between games could give Bell enough time to heal. But the 21-year-old is simply thankful he didn't leave the field on a stretcher.

"I'm glad that nothing seriously wrong happened," he said. "It was definitely an ugly hit. I don't remember the exact play. But once I seen the film, I know what it looks like now."

Bell leads the Steelers with 528 yards rushing and five touchdowns. He is also fifth on the team with 33 receptions. Taken in the second round of the 2013 draft because of his versatility, he has given Pittsburgh's struggling running game some needed stability.

If Bell can't play, the Steelers will turn to Jonathan Dwyer or Felix Jones when they face the Dolphins. Whoever is in the backfield will play behind an offensive line that can't seem to stay healthy.

Pittsburgh lost center Fernando Velasco for the season with an Achilles injury, making him the second center to end the year on injured reserve. Perennial Pro Bowler Maurkice Pouncey played just eight snaps this season before tearing the ACL in his right knee.

Guard David DeCastro (foot), left tackle Kelvin Beachum (knee) and reserve tackle Mike Adams (ankle) are also hurt, forcing the Steelers to scramble to find five healthy linemen for practice on Monday. They signed well-traveled center Eric Olsen and tackle Rashad Butler on Saturday, though Butler's stay was short-lived after he left the team on Monday due to "personal reasons."

Cody Wallace, signed for depth purposes in September, anticipates making the first start of his NFL career against the Dolphins. If he starts, the Steelers will have their seventh different starting line combination this season.

"This year has been kind of unusual in that way," Wallace said. "But we're fortunate to have enough guys to step in and make an impact after the starter got hurt. I'm glad to be part of that group, too, but this really has been an interesting year in that regard."

Pittsburgh's unlikely hopes for a playoff berth remain alive after losses by San Diego, the New York Jets and Tennessee on Sunday. If the Steelers can win out—they face just one team with a winning record the rest of the way—and get a dash of help, they could find their way from 0-4 to the postseason.

"We're still in this thing," Dwyer said. "It's crazy. You know the things we wanted to happen this past weekend, they happened. We know if we start stacking wins, we'll see things work out our way."

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