Jerome Bettis coming up lame in advance of and doubtful for the regular-season opener constitutes a bump in the road much more than it does a major blow as far as the Steelers are concerned.
On the list of irreplaceable players, Bettis ranks well down the chart, Hall-of-Fame credentials and all.
If you're talking players the Steelers can least afford to lose, start with left offensive tackle Marvel Smith.
If Smith goes down for any length of time, it's a problem. Barrett Brooks is the only veteran backup available, and even the Steelers don't trust Brooks as a capable replacement beyond a quarter or two, or a game or two.
Right tackle Max Starks, likewise, is also relatively invaluable, even though Starks has yet to make his first NFL start. Rookie Trei Essex, the other backup at tackle, has potential but remains far enough away from realizing it that he won't dress on game day.
Left guard Alan Faneca also falls into the have-to-have-him category. Faneca is perhaps the best offensive lineman in the NFL (and might still be the long-term option at left tackle should Smith be lost for an extended stretch, as was the case in 2003).
On defense, linebacker James Farrior is a reigning All-Pro and strong safety Troy Polamalu is poised to become one. Both are three-down players and indispensable in whatever package the Steelers employ.
At outside linebacker, the Steelers are already shy one starter, which means current first-teamers Clark Haggans and James Harrison are pivotal figures. As long as one of the big three at the position is injured, as Joey Porter currently is, the other two become guys the Steelers absolutely, positively have to have healthy.
Kicker Jeff Reed, based on the difference he can make, is also more essential than Bettis.
As for the running game, that'll live and die with the offensive line, as always.
The Steelers would have preferred that Bettis handle things until Duce Staley returned to full strength, but they'll still line up and run the ball on Sept. 11 against Tennessee.
If they're running "Fast" Willie Parker on first and second down and utilizing Verron Haynes on third down, so be it.
Parker could become this year's Ben Roethlisberger _ the best player at his position who only got a chance to play because injury forced him into the lineup.
The former rookie-free agent has a Roethlisberger-like upside.
"I'm not concerned," coach Bill Cowher said of potentially starting Parker. "I'm rather excited."
Should Parker fail to dazzle, someone else will have to (tight end Heath Miller, perhaps).
Either way, the Steelers weren't anticipating another 250 carries and 941 rushing yards from The Bus in the first place.
His injury is more a personal setback than a potentially devastating situation for the Steelers.