Robert Griffin III and the Redskins aim for a season sweep of the Cowboys, the NFC East title and a playoff berth. (Jonathan Newton/The Washington Post)

The Washington Redskins’ most important game in the last five years is almost here. On Sunday, the team faces the Dallas Cowboys with a playoff berth and the NFC East title on the line.

Winners of six straight, the Redskins will try to continue their post-bye hot streak and record their first 10-win season since 2005 and only their third since 1991 when they won the Super Bowl.

The Redskins believe that they have a special team and that they are fully capable of pulling off the victory and heading into the playoffs riding a huge wave of momentum.

The Redskins enter the game as three-point favorites and are 10-5 against the spread this season. But, they’re 3-3 against the spread when picked as the favorite.

A win would give them their first seven-game win streak since 1996.

Here are five storylines to follow Sunday night.

 1.) Chicago Bears, Minnesota Vikings – Before they even take the field against the Cowboys for their 8:20 p.m. kickoff, the Redskins could know where they stand in terms of the postseason because of how games earlier in the day play out. If the Bears lose at Detroit, and the Vikings lose at home to the Packers, the Redskins earn a playoff berth win, lose or draw. With a loss to the Cowboys, and losses by Chicago and Minnesota, Washington would land a wild card bid. But, if either the Bears or Vikings, or both, win, then the Redskins can only make the playoffs with a victory over the Cowboys. The Redskins insist that they won’t be scoreboard watching on Sunday, however, and that their only goal is defeating Dallas and earning their first NFC East title since 1999.

2.) Griffin’s performance – The Redskins will need a big game out of their newly-selected Pro Bowl quarterback, and it’ll be interesting to see what type of a game plan offensive coordinator Kyle Shanahan comes up with for the Cowboys. Will we see pocket-passer RGIII, or dual-threat RGIII? Shanahan against the Eagles called only one designed run in Griffin’s first game back from the sprained  lateral collateral ligament, but Griffin said on Wednesday that he expects to have more freedom this week. Redskins players say ultimately, it doesn’t really matter which plan Shanahan opts for because Griffin has proven he can win running a traditional attack, and that he can win while running more of a pistol/zone-read option heavy scheme. Another intriguing aspect will center around how Griffin fares against a defense that has faced him before. His numbers declined in his rematches with both the New York Giants and the Philadelphia Eagles. He threw for 258 yards and two touchdowns on 20-for-28 passing and rushed for 89 yards on nine carries in the first Giants game, and 163 yards and a touchdown on 13-for-21 passing, and rushed for 72 yards on five carries in the rematch. Against the Eagles, Griffin completed 14 of 15 passes for 200 yards and four touchdowns and rushed for 84 yards on 12 carries in their first meeting, and then completed 16 of 24 yards for 198 yards and two touchdowns and an interception and rushed for four yards on two carries. But Kyle Shanahan dismissed the notion that opponents have significant advantages in their second games against Griffin because the Redskins also have better familiarity on how teams will try to play them the second time around and can adjust accordingly.

3.) Right tackle – Much of Griffin’s success – and the success of running back Alfred Morris, whose production has been key all season – will hinge on the offensive line’s ability to hold their own against a disruptive Dallas front that recorded four sacks in their first game against the Redskins. The biggest area of concern has to be right tackle, where either Maurice Hurt, who has played only one game there, or Tyler Polumbus (concussion) will spend much of the night trying to neutralize outside linebacker Anthony Spencer, who sacked Griffin twice on Thanksgiving Day. Redskins coaches said that they were pleased with Hurt’s play last week against Philadelphia. However, he was far from perfect, and whiffed several times both on pass and run blocks. Several of Dallas’s other top defenders — DeMarcus Ware (elbow, shoulder) Jay Ratliff (groin) and Jason Hatcher (thigh) — are questionable for the game.

4.) Dez Bryant versus Redskins secondary — The wideout is on a hot streak in the second half of the season, averaging seven catches for 120 yards and 1.5 touchdowns a game in his last six outings. In the first game against Washington, he recorded eight catches for 145 yards and two touchdowns, including an 85-yarder. Last week against the Saints, he recorded nine catches for a season-high 224 yards and two touchdowns. Cornerbacks DeAngelo Hall and Josh Wilson will have their hands full as they take turns matching up with Bryant. They likely will need help from their safeties, but the Redskins have been hurt all year by poor play from their patchwork safety unit. Washington’s defensive backs can’t afford to blow assignments and must be on-point with their recognition, anticipation and reaction skills. Struggles in the secondary could wind up costing the Redskins their postseason hopes.

5.) Getting to Romo – Washington’s defensive linemen and linebackers can help their defensive backs out a good deal by putting Tony Romo under frequent duress. But it’s not enough to flush Romo out of the pocket. The Redskins must get to the quarterback and sack or hit him. “I don’t want him running around, first of all. If we can kind of eliminate that, that would be No. 1,” defensive coordinator Jim Haslett says. “It’s hard to contain the guy first of all because I think he’s a heck of a football player. I’ve always felt that way about him. He’s got a great feel for getting out of the pocket and moving around.” The Redskins allowed Romo to put together a big second half in their first meeting, and he almost pulled off a comeback. The defense is coming off of one of its best outings of the season, recording five sacks and two turnovers against Philadelphia. A similar effort will be needed Sunday night.