PITTSBURGH (AP) Josh Harris could tell by the silence that it was serious. There was no need to glance at the replay.
The instant the helmet of Cincinnati safety Reggie Nelson slammed into the right knee of Pittsburgh running back Le'Veon Bell in the third quarter Sunday night, the bubbling euphoria that gripped Heinz Field only moments earlier vanished.
Bell, the budding second-year running back, lay in agony on the turf. Harris, an undrafted free agent turned unlikely backup, suddenly found himself prepping to go into the biggest game of the season.
''It was a shock at first,'' Harris said.
For the rest of the Steelers, too. Pittsburgh held on to defeat the Cincinnati Bengals 27-17 and win the AFC North. Coach Mike Tomlin stressed there was no major structural damage to Bell's knee, but the Steelers (11-5) head into Saturday's wild-card game against Baltimore (10-6) wondering if their chances for a seventh Vince Lombardi Trophy hinge on Harris and Dri Archer.
That's couple of rookies who have combined for 56 yards rushing in their brief careers.
No pressure or anything.
''At the end of the day, they have me here to do what I'm here to do,'' Harris said.
Maybe, but the Steelers are hoping Harris doesn't have to clock in. Bell underwent further testing Monday to judge the severity of what the team is calling a hyperextended knee. While the 22-year-old has joked in the past that he's a quick healer, bouncing back on a short week on a bum leg to face the Ravens appears daunting.
''Injuries happen,'' center Maurkice Pouncey said. ''If he can't go the next man has to step up and play just like him or better.''
Good luck with that.
Bell's constantly churning knees were so vital to Pittsburgh's resurgence that in the vote for team MVP, the Steelers selected him over quarterback Ben Roethlisberger and wide receiver Antonio Brown. They did so even though the two established stars put up numbers hard to duplicate in a video game, let alone real life. Bell set club records for all-purpose yards (2,215) and receptions by a running back (83). Oh, and he did it without fumbling once.
His talent became so prevalent the Steelers considered LeGarrette Blount expendable. Pittsburgh cut the well-traveled veteran in November after Blount headed to the locker room with the clock still running in a win over Tennessee, a silent but deliberate protest over a lack of touches.
The Steelers didn't go looking for a free agent to replace Blount, instead promoting Harris from the practice squad. Harris shared backup duties with Archer, a third-round pick who has struggled to find any traction. Neither saw much action after Blount left. They had six carries combined following Blount's departure until Bell half-jogged/half-limped to the sideline in the third quarter Sunday night.
Harris appeared to provide a momentary spark in the fourth quarter, sprinting over right guard for a 60-yard gain. The play was called back due to a holding penalty on Ramon Foster, though it did little to dampen Harris' optimism that he can play.
''It was just great blocking up front, I just made one cut and I was out,'' he said. ''It (stinks) that it was called back, but the fact that run happened showed everyone I can actually play and do things like that.''
Harris managed just 7 yards on five carries on the runs that did count, while Archer caught two passes for 19 yards. Not exactly Bell-like with the NFL's fourth-ranked run defense looming.
The Steelers will need to get something going on the ground to prevent Baltimore pass rush specialists Elvis Dumervil and Terrell Suggs from teeing off on Roethlisberger.
The quarterback tossed six touchdowns in a 43-23 victory on Nov. 2, the second half of a two-game stretch in which Roethlisberger found the end zone a league-record 12 times.
He has cooled off considerably since as the Steelers became more reliant on Bell to eat up clock and yardage behind a rapidly improving offensive line. That formula will have to be altered if Bell is forced to sit.
''We can grow at every point,'' Pouncey said. ''That means sticking with what we're always good at and letting Dri be the man he got drafted for.''
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