No Washington Redskins tailback has posted as many as 80 yards on the ground in any of their five games this season. And on Monday night, they will face their biggest test to date, a Philadelphia Eagles defense that has smothered running backs all season.

How good has Philadelphia’s rush defense been? The Chiefs’ Kareem Hunt managed 81 yards in Week 2, but in the Eagles’ other five games, no other running back has topped 35.

The Redskins hope they’ll be the team that can solve the Eagles’ dynamic front four, and they likely will turn to Rob Kelley to do it. Kelley is coming off an ankle injury and while he was limited in practice both Thursday and Friday, he says he expects to be healthy enough to play Monday. If that’s the case, Redskins Coach Jay Gruden said Kelley will again be slotted as the Redskins’ No. 1 running back. Kelley missed the Week 3 game against the Raiders with a rib injury and missed Sunday’s win over San Francisco with an ankle injury.

“I was expecting some rust,” the second-year running back said after practice Friday, “but I had a few good runs the past few days. … We’ll figure out in the game if there’s rust or not.”

In his absence, Chris Thompson has shown he’s a strong receiving threat out of the backfield — he had 150 receiving yards against the Raiders and 105 against the 49ers — and Samaje Perine has been a serviceable ball-carrier.

Kelley said he’s not too worried about how the carries are divided up — as long as the Redskins can steal a win on the road.

“I think me getting all the carries, I think it wouldn’t be beneficial to the team, especially at this point,” he said. “Then you have Chris playing out of his mind right now, so why would you do that? Whatever Coach needs, I’m there for. If he wants me to run it the whole time, I can run it the whole time. If he wants to split carries, I can do that, too.”

Asked why the Eagles’ defensive front is so good, Kelley didn’t even pause. “They pay a lot of money for their front. That’s the obvious thing,” he said.

And it’s true. The unit is led by Fletcher Cox, who last year signed a contract that could be be worth $103 million, along with Vinny Curry, who last year signed a deal that could be worth $47.5 million, and Brandon Graham. In the offseason, the Eagles drafted Derek Barnett in the first round and added Timmy Jernigan, a former second-rounder, in a trade with Baltimore.

“To be good against the run, you have to have good players, and they have good players across the board,” Gruden said. “And it’s not just their first four. They’re bringing backups, and they’re just as good.”

After studying tape, Gruden says the Eagles’ defense essentially has eliminated opposing teams’ ground game. They put foes in deep holes and force third-and-long situations. If Washington wants to find success on the ground, they will have to stay committed to the run and find some semblance of success on first downs.

“We’ve got to make sure that when we do run the ball, we try to make positive yards, even if it’s three yards, four yards,” Gruden said. “That’s a good run for us to keep us in positive down and distances.”

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