Derek Carr has a fractured back, and it could be a big blow to the Raiders' playoff hopes

The Oakland Raiders' season took an ugly turn in Week 4 when Derek Carr left the game with a back injury.

Initially, the injury was thought to be back spasms, but on Monday, the Raiders announced that Carr suffered a transverse process fracture in his back and is expected to miss two to six weeks.

Two weeks, however, may be an optimistic projection, judging from the reaction of Tony Romo - who had the same injury in 2014 - on the broadcast.

"Oh boy, Jim [Nantz], oh no," Romo said as he saw Carr on the ground. "

For the Raiders, the injury is bad news unto itself, but it could have a deeper impact on their season if Carr misses significant time.

Thought to be the best team in the AFC West at the beginning of the season, the Raiders are now instead in a race with the 4-0 Kansas City Chiefs and the 3-1 Denver Broncos, both of whom look like possible Super Bowl contenders.

Likewise, the rest of the AFC is no cake-walk, and if the Raiders can't win the division, the fight for the two Wild Card spots will be tough. The AFC East sports the New England Patriots, the surprise 3-1 Buffalo Bills, and the super-surprise 2-2 New York Jets. The AFC South has three potential playoff teams in the Tennessee Titans, Houston Texans, and Jacksonville Jaguars. And the AFC North has the Pittsburgh Steelers and the Baltimore Ravens.

The Raiders are a deep team, but much of it comes down to Carr. Last season, when Carr got injured in Week 16, the team lost its next game, then lost the first game of the playoffs. This year, E.J. Manuel is the backup quarterback instead of Matt McGloin and Connor Cook, but leaks have been springing around the Raiders. Top receiver Amari Cooper has an ugly case of the drops this season, and Marshawn Lynch, the Raiders lead running back, has seen his yardage and yards per carry fall each week of the season.

The Raiders' next five games come against the Baltimore Ravens, Los Angeles Chargers, Chiefs, Bills, and Miami Dolphins before they have a bye week. If Carr were to miss all five games and return after the bye, it's possible the Raiders could go 3-2 or 2-3 over that stretch and sit at 5-4 or 4-5 when Carr returns with enough time to make a playoff push. If he misses even less time, obviously the Raiders will be in even better positions.

But in a surprisingly stout AFC, the Raiders now face an uphill climb without their franchise quarterback.