As of 2016, nearly 59 percent of teams that start the season 2-0 will reach the playoffs, according to Joe Osborne ofOddsShark. On Sunday, the Dallas Cowboys and Denver Broncos will face off to try to grab early leads in their respective divisions.The Broncos will be a tough opponent for the Cowboys for a variety of reasons. The biggest might be their home-field (and altitude) advantage. According to Warren Sharp of Sharp Football Analysis, the Broncos were 18-1 at home in the first two weeks of the season since 2000. After their win over the Los Angeles Chargers Monday, that record has moved to 19-1. A big reason why is that teams just aren't in good enough condition to play in Denver early in the season.Aside from the altitude, Denver also has one of the best defenses in the NFL. The Broncos finished in the top five in both points and yards allowed in 2016. If the Cowboys want to beat Sunday's opponents for the first time in 22 years, they will need to find a way to score on this elite defense.Read on for a list of the seven biggest keys to a Dallas victory on Sunday in Denver.Begin Slideshow Click here to read full news..