The Redskins.com crew breaks down the key players and matchups to keep an eye on during Sunday's Redskins-Cardinals 2016 Week 13 showdown at University of Phoenix Stadium in Glendale, Ariz.

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HAVE VERNON CRACK THE CODEEntering Week 13 action, the Arizona Cardinals are not only the No. 1-overall rated defensive unit in the NFL, they've given opposing tight ends fits, as they haven't allowed a single touchdown from the position.

Carolina Panthers tight end Greg Olsen – who is second among tight ends in receptions this season with 58 – recorded just a single catch for 11 yards against the Cardinals. Vikings tight end Kyle Rudolph, meanwhile, had just two receptions for 12 yards two weeks against Arizona.

While Redskins No. 1 tight end Jordan Reed is out with a shoulder injury for Sunday's game, Washington knows that Vernon Davis can fill the void.

Arguably the league's best No. 2 tight end in the NFL, Davis' athleticism is nearly on the same level as Reed's and the 32-year-old has quite a few explosive plays this season to back up that claim.

If they have to go heavy with Davis on Sunday, the Redskins know they won't really have to make many changes in the playbook if any.

"We're going to keep the standard concepts, the plays that we have that we like, but we expect Vernon or Derek [Carrier] to be able to do them," Gruden said. "We might have less of a certain package – maybe the three-tight-end sets, or something like that – but we'll still carry about everything that we have and just let Vernon or Derek do it and hope that Jordan can play."

Even though Davis is now in his 11th season in the NFL, the University of Maryland product feels he's only getting better and better. Sunday will be another chance to prove that the Redskins made the right decision in bringing him in.

"I tell everyone the same thing: when I lose my speed then I'll hang it up," Davis said. "But I still have my speed. I can still run, run well. With that, I can continue to play this game."

(Stephen Czarda)

DON'T LET FITZGERALD HAVE A BIG DAY
Like Davis, Cardinals wide receiver Larry Fitzgerald, 33, is showing no signs of slowing down any time soon.

A nine-time Pro Bowler, Fitzgerald is only four receptions away from becoming only the fifth player in NFL history with 1,110 receptions, and with seven catches, would bump up to third all-time in the category behind only Jerry Rice and Tony Gonzalez.

While the Cardinals wide receiving corps has struggled as a whole some this season, the University of Pittsburgh product is currently second in the NFL in receptions (78) and 11th in receiving yards (802).

While Fitzgerald has had his way with top cornerbacks over the years, the Redskins could use All-Pro Josh Norman to their disposal and have him travel with the 33-year-old wherever he goes.

The Redskins did this some with Dez Bryant in Week 2 and Odell Beckham Jr. in week 3.

 "Yeah, anytime that we're in a situation when you match a corner on a wideout – if you're truly matching him no matter where he goes, he goes," Redskins defensive coordinator Joe Barry said. "Now, there's parameters based on that when you're in man, when you're in zone, things like that. But yes, there will be times per call – if the call dictates that Josh matches No. 11 [Fitzgerald], he's going to match him even if he's lined up in the backfield."

(Stephen Czarda)

GET 'FAT ROB' BACK ON TRACK
For the first time in four games as the Redskins' starting running back, Rob Kelley didn't have a strong, notable performance against the Cowboys. After averaging 107 yards per game against Cincinnati, Minnesota and Green Bay, Kelley was limited to just 37 yards on 14 carries in a Thanksgiving Day loss to Dallas. However, that didn't discourage Redskins head coach Jay Gruden.

"Robert ran it extremely hard, I mean he ran hard and his stats do him injustice for as hard as he ran so I'm happy the way he ran the ball," Gruden said the day after Washington's five-point loss in Texas.

Gruden was quick to credit the Cowboys, which rank third in the NFL in rushing yards allowed per game with 82.3, for having "great movement" up front that he didn't think his team handled very well. Another problem was that Washington was playing catchup for most of the game, especially in second half.

"We were having success through the air, in the second half we were down by a couple scores and we felt like through the air was the way to try and make up some chunks of yards and get back in the game which we did," Gruden said. "Unfortunately, we couldn't get the stops when we needed them and it didn't work out but we're not going to abandon the running game, just yesterday was just more of a pass attack game because of the situation that we were in."

However, this week provides another challenge for Kelley, who will take on an Arizona front that ranks sixth in the NFL in yards allowed per carry at 3.7. But Kelley's biggest challenge may lie in himself as the NFL season is almost three-quarters finished.

Kelley has become the workhorse for Washington, averaging a hair more than 20 carries per game since becoming the starter. In his college career at Tulane, Kelley never carried the ball more than 16 times in a game. Counting his carries in the preseason, Kelley has rushed 136 times for the Redskins in 2016. His career-high for carries in a season at Tulane was 98 in 2013.

"I don't know, like sometimes I'm feel I'm about to hit the (rookie) wall that they talk about," Kelley said. "I really don't know what it is, I guess it's just crashing, but when I get out there and start playing football I just all forget about it. I think I definitely get it in meetings though sometimes, stuff start getting repetitive to you and stuff like that."

With the production that Kelley has given the Redskins, Gruden and his staff will surely hope that Kelley does not slow down. He currently ranks eighth among NFL running backs with 4.7 yards per carry. In his four starts, Washington is averaging 488.5 yards per game with three 500-plus yard games.

(Perry Mattern)

ALL EYES ON DAVID JOHNSON
The Redskins are in for a unique challenge this weekend in Cardinals running back David Johnson. The second-year player has already become known as a very effective running back in the NFL and has also emerged as an extremely dominant threat in the passing game.

"[Johnson's] one of the top backs whether he's running the ball or catching the ball out of the backfield," defensive end Chris Baker said. "He always finds a way to make big plays. He's got a lot of yards per carry and after catch. It'll be important for us to really rally and gang tackle because if we just leave him one-on-one with a DB or one-on-one with a linebacker, he's probably going to break tackles. So we've got to do a good job as a defense gang tackling."

Johnson is currently ranked third in the league in rushing yards this season (921) and has also had 100 yards from scrimmage in every game he has played in this year. His 11 consecutive outings make him only the second person in NFL history to accomplish that mark, along with former Colts back Edgerrin James. If he is able to finish all 16 games this season with at least 100 yards from scrimmage, he will become the first player in NFL history to do so.

But the Redskins will be attempting to do everything in their power on Sunday to break that streak.  The defense has not allowed a back to rush for 100 yards or more in the past three games since the bye and look to continue that trend on this week's road trip. Stopping this style of back, however, will require a bit of a different defensive plan.

"When you think of a guy that can move outside and catch the ball, you think of a little scat-back type guy that doesn't run between the tackles, but (Johnson) runs between the tackles as good as he catches the ball," head coach Jay Gruden said. "I mean, he is probably the best all-around back there is in the National Football League right now as far as being able to move outside, be a great route runner but also run between the tackles and run outside with his speed. So it's going to be a matchup problem. He's been a matchup problem for everybody this year. He's got 950 yards rushing and he's got nine touchdowns and a bunch of catches, so like I said, when you have great players like that, you study them, you study their scheme, you try to match up, mix up your intent – man, zone, all that stuff – and you do the best you can and try to get your pass rush home." 

With 13 total touchdowns this season, Johnson is a threat not only to break plays open all over the field, but also specifically in the red zone where the Redskins will look to limit the Cardinals, who have struggled to put a significant amount of points on the board, not scoring over 30 since Week 5.

By focusing on limiting Johnson, the defense is hoping to come back from some of the difficulties they had against the Cowboys last week and show exactly what it can do.

"[We're] just trying to fine tune things," linebacker Ryan Kerrigan said. "Just trying to tighten up whatever deficiencies we may have and trying to improve the things we already do well and put a good performance out there Sunday."

(Alaina Getzenberg)