With inside linebacker Perry Riley Jr. battling a knee injury, second-year Nebraska product Will Compton may be asked to start -- or at the very least play an expanded role -- Sunday against the Arizona Cardinals.

"Yes, it would be Will Compton," Redskins head coach Jay Gruden said Wednesday when asked who would start if Riley Jr. can't go. "He got all the reps today, did a good job. Will is more than ready to go. Hopefully Perry gets well. If not, we have that position covered."

Taking reps with the first-team defense at Wednesday's practice, Compton said he's preparing like a starter this week.

"I'll prepare like the starter just like I have week in and week out," he said. "The sense of urgency obviously rises a little bit, so prepare, prepare, prepare and I'll be prepared."

Undrafted in 2013, Compton worked his way onto the Redskins' practice squad before making the active roster and eventually making his debut in the regular season finale.

Appearing in all five games this season, Compton has recorded eight tackles as a substitute for Riley Jr. and Keenan Robinson.

"The first part of the season, I had the responsibility of going in whether one of them goes down no matter what," he said. "So I figured I'd get in at some point throughout the year with it being a long season, but it's what I wanted, so I've got to be prepared and show out."

Compton said one comforting aspect of being in the starting lineup, if he is thrust into that role on Sunday, is that Robinson will be alongside him instructing the defense.

"That'll be nice knowing that Keenan will be out there making the calls and initial calls and things like that," he said. "A lot of my game is based off tendencies and recognizing and anticipating, so I'll be ready to do that if needed, but that's where my strong point is and that's where I like to try to be a step ahead."

Facing an Arizona Cardinals offense that does a great job with ball security – they have only two lost fumbles and no interceptions this season – Compton said his teammates and he must be prepared for constant change before the snap.

"They motion a lot, they shift a lot, so we've got to keep our eyes on our work and know our responsibility," he said. "We're tweaking as far as where help comes from sometimes, but they do a lot of shifting."

One of the players that move around most is running back Andre Ellington. Last week, rookie quarterback Logan Thomas hit Ellington for an 81-yard touchdown.  

"[He's] a good running back that they'll flex out, so they'll play him as a receiver sometimes," Compton said. "So we've just got to be prepared. We've got to be ready to go. We've got to know what they'll throw at us and play the down."

Riley Jr., meanwhile, could possibly miss his first game since Week 11 of the 2010 season.

Starting the team's last 45 games, Riley Jr. has been one of the most consistent players on the defense.

Last season, the LSU product recorded a team-high 115 tackles.

"We want him to go, but we'll see how he does," said Gruden.

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