The Philadelphia Eagles and the Chicago Bears meet in Week 9 in a rematch of last year's NFC Wild-Card matchup. Both teams haven't lived up to their immense potential, but that should make for a good ball game.

Both sides have their strengths, and it will take a particularly strong performance in some areas for the Eagles to win. Whether the Eagles execute or not, this game should be a one-score affair at the finish.

Here are two major X-Factors for the Eagles ahead of their matchup with the Bears:

2. The execution of the offensive line

Despite their struggles, the Bears still have a nasty pass-rushing group. Khalil Mack is obviously a monster, and they have plenty of supplementary players to go along with him. The coverage behind that Chicago front seven is also strong, making quarterbacks hold the ball too long and absorb sacks. If the Eagles want to move the ball more effectively than they did in their playoff matchup with the Bears last season, Wentz has to have a clean pocket.

The Eagles have allowed just around league average when it comes to sacks, and that won't cut it against the Bears. Right tackle Lane Johnson will probably draw Mack for most of the day, with help from tight ends Dallas Goedert and Zach Ertz. If Mack lines up against fill-in tackle Andre Dillard, the Eagles must provide help. Leaving Mack against a rookie like Dillard is the definition of a recipe for disaster.

1. The performance of the defensive backs

The Philadelphia secondary has struggled mightily to this point. They're currently ranked as the 21st best pass defense in the NFL, but this game is a huge opportunity to fix their problems. The cornerbacks should be licking their chops ahead of a matchup with Chicago signal-caller Mitchell Trubisky. He has been horrible so far, and there's no real indication that he's anywhere near improving.

If the Eagles are ever going to improve against the pass, they have to do it against the Bears. Top cornerback Ronald Darby should shadow Chicago receiver Allen Robinson around the field, creating a somewhat even matchup for Philly. The real problem is cornerback Jalen Mills, who's an extremely inconsistent player. He shows flashes of greatness but also bites on just about every double move thrown his way.

The safeties should have no issue shutting down the Bears' secondary weapons. Chicago running back Tarik Cohen hasn't been nearly as productive as a year ago, and should an easy assignment for either Rodney McLeod or Malcolm Jenkins. Chicago has seen virtually no production from their carousel of tight ends, so no worries there either.

As long as this defensive backfield can do their job and force Trubisky into tough throws, the Eagles have a great shot at winning.