The Washington Redskins on Sunday face the 4-2 Buffalo Bills in Toronto, and aim to snap a two-game losing streak and regain the positive form with which they opened the season.

 The Redskins have had to do a good bit of reshuffling because of another round of injuries at key positions.

 Here are five story lines to follow as Washington takes on Buffalo.

 1.) The injury bug: The Redskins already are down four offensive starters (Santana Moss, Tim Hightower, Chris Cooley and Kory Lichtensteiger) and likely will be without a fifth (Trent Williams) for another week. The team could be without some defensive starters as well as cornerback DeAngelo Hall didn’t practice Wednesday or Thursday and linebacker London Fletcher and free safety Oshiomogho Atogwe’s statuses remain uncertain as well because of hamstring and knee injuries, respectively. Those are some significant holes to fill.

 2.) Revamped RB unit: Ryan Torain appears most likely to start for the Redskins now that Hightower is out, and the third-year pro said he’s eager to prove he can consistently execute at a high level and that his big game against the Rams a couple weeks ago wasn’t a fluke. Rookie Roy Helu will be counted on to provide a spark, and both he and Torain have a tall task in matching Hightower’s pass-protection prowess. It still wouldn’t be a surprise to see the Redskins activate rookie Evan Royster from the practice squad this weekend.

3.) Run defense: Fred Jackson is a monster, and the Bills will give him a steady dose of carries, presenting a significant challenge for Washington’s defense. The Redskins have gotten steamrolled in losses, allowing their foes to top 170 yards in each defeat. For the season, Washington has allowed 153 yards per game. If Washington can’t find a way to slow Jackson, the Bills will have no problem dominating the clock and will wear down the Redskins just like the Panthers did last week.

 4.) Young receivers: With Santana Moss shelved for three to six weeks, the Redskins are counting on young receivers Anthony Armstrong (second-year pro), Niles Paul (rookie), Leonard Hankerson (rookie) and Terrence Austin (second year) to step up and team with veteran Jabar Gaffney in the passing game. Armstrong played significantly last season, but the other youngsters must grow up in a hurry to provide big plays for a stagnant offense.

 5.) Beck’s progression: Both Coach Mike Shanahan and offensive coordinator Kyle Shanahan praised John Beck’s play in his first full game at Carolina last week. After pacing Beck in the first half by calling 18 rushing plays in the first half, Kyle Shanahan put more on the quarterback in the second half and Beck did a solid job. The quarterback missed on some opportunities, but his coaches believe Beck can only get better. But he faces a tough test this week going up against a defense that ranks second in the NFL with 12 interceptions. And to further stoke the pressure-cooker, the Bills average 31.3 points per game, meaning Beck & Co. will have to keep up.