PITTSBURGH — Mike Tomlin likens each Pittsburgh Steelers opponent to “nameless gray faces,” the coach’s way of telling his players to treat every game the same regardless of who happens to be across the line of scrimmage.

Not all gray faces, however, are created equal. And they’re not all nameless either.

When Pittsburgh (3-1) welcomes Jacksonville (2-2) to Heinz Field on Sunday, the league’s second-ranked defense doesn’t need to be told about the big kid in the Jaguars’ backfield. The Steelers are well aware of the 240 pounds of controlled fury rookie running back Leonard Fournette brings each time the ball is in his hands. Last they checked, they’re not exactly small themselves.

“We’re 6-6, 300 pounds, you think we’re not big dudes?” defensive end Stephon Tuitt said. “We’re big, athletic fast dudes. We know he is going to be at the same time. This is the type of matchup that we like, and they’re going to know that this Sunday.”

Funny, it didn’t look like Pittsburgh enjoyed itself the last time it faced a power run team. The Bears plowed through the Steelers for 222 yards in an overtime upset two weeks ago. Though Pittsburgh held Baltimore in check in a one-sided victory in Week 4, the Ravens ran the ball only 15 times. Jacksonville might top that number in the first quarter if the quartet led by Fournette gets going.

“We try to think of it almost like a Chicago redo because they have a myriad of backs and because they rely on the run,” Steelers defensive end Cam Heyward said. “We have a chance to test ourselves again.”

And the Jaguars have a chance to prove the promise they’ve shown during their competent start isn’t a mirage. Jacksonville squandered a shot at generating real early-season momentum when it fell in overtime to the New York Jets last week, though it’s hard to blame Fournette, who racked up 145 combined yards and scored for the fourth straight game.

The only thing Fournette hasn’t done is showcase the breakaway speed that comes along with all that brawn. His longest run is 17 yards. The Steelers have given up at least one run of 25 yards or more in each of their last three games.