Before the start of the 2013 NFL season, the Dallas Cowboys were considered one of the favorites to win the NFC East. Three weeks into the year, the team may be proving the odds-makers right.

The Cowboys have only played 19 percent of their schedule, but their playoff chances appear to be very good. At 2-1, the Cowboys are the only team in the division with a record above. 500. The New York Giants and Washington Redskins remain winless, and a loss in Week Four could essentially end either one of their seasons. The Philadelphia Eagles are one game back at 1-2, but haven’t looked like a playoff team with a rather suspect defense.

With the rest of the division faltering, the Cowboys are sitting pretty in the NFC East. This week, however, Dallas encountered an issue that could affect their quest to make the postseason for the first time since 2009. The team has learned that Anthony Spencer must undergo season ending microfracture surgery. The veteran defensive end had a procedure done on his left knee in July, which kept him out of the opener. Spencer came back in Week Two against the Kansas City Chiefs, but was unable to take the field afterwards.

In the past few years, only DeMarcus Ware has been a more consistent player for the Dallas defense. In 2012, Spencer registered a career-high 11 sacks. From 2009-2012, he missed just two games, accumulating at least 50 tackles in each year.

The injury gives George Selvie an opportunity to receive more playing time. He has filled in as a starter for Spencer this year, and will be asked to do so for the final 13 games. The fourth-year defensive end has done a more than serviceable job in Spencer’s place, registering two sacks in the first three games. Selvie is trying to finally stick with a team after bouncing around the league, playing on four different teams in as many seasons. Before 2013, he never had more than 1.5 sacks in a season.

Nick Hayden is in a similar position as Selvie. He’s struggled to secure a job in the NFL since being drafted in 2008, playing more than 10 games just once and going all of 2012 without a job. He has started every game for the Cowboys this season and is looking to remain as a starting defensive tackle. Playing for a team that has relied primarily on Ware and Spencer up front for the past few years, Hayden will likely be called upon to be a force on Dallas’s line.

Even with Spencer limited in the first three games, the Cowboys have been able to get to the quarterback. Only the Chiefs have more than their 13 sacks. Dallas’s one weakness in 2013 has come in pass coverage. They rank 22nd in the NFL in yards allowed through the air.

Given the injury to Spencer and questions on the defensive line, it won’t be a surprise to see the Cowboys regress in their ability to get to the quarterback. As a result, defensive backs like Morris Claiborne may have to do a better job against the pass. He was drafted No.6 overall in 2012, and the microscope will likely be on the 23-year-old to fulfill high expectations. Claiborne is playing with a dislocated shoulder, but needs to perform like he’s injury-free if he continues to take the field. He seems to be on the right track after a solid effort against the St. Louis Rams.

Spencer is expected to be completely healthy in the early pat of 2014. He’ll be a free agent in the offseason since Dallas gave him the franchise tag.