When David Johnson went down with a wrist injury on Sunday, the severity was unclear. A day later, it still remains uncertain just how long Johnson will be out, but all signs indicate that he will miss some time.

On Monday, the Cardinals revealed that Johnson suffered a dislocated wrist, but he's seeking a second opinion.

According to NFL Network's Ian Rapoport, Johnson is expected to miss an "extended period of time" and could even land on injured reserve. ESPN's Chris Mortensen reported that the timeline for his recovery could be 2-4 weeks or maybe even 3-4 months. A source told ESPN's Josh Weinfuss that the injury is "not good." And the team's official website reports that the second opinion if confirmed will lead to wrist surgery:

So, it sounds like the Cardinals and Johnson are still gathering information from doctors and weighing their options. But it also sounds like they can expect to be without their most important player for a while.

If Johnson is forced to miss a large chunk of time, it wouldn't be surprising to see the Cardinals re-sign Chris Johnson, who has a history with the team, having played for them in each of the past two seasons.

They could also stick with Kerwynn Williams and Andre Ellington. Or maybe they'll bring in someone from the outside. Regardless, from a Fantasy perspective, it appears to be a nightmare.

It's also a nightmare for the Cardinals. Johnson is irreplaceable. He's arguably the best all-around running back in football -- Le'Veon Bell is the only other running back in the discussion. Last year, Johnson led the league in yards from scrimmage with 2,118. He was such a good receiver that Pro Football Focus named Johnson -- a running back -- the best receiver of the 2016 season. If not for the Cardinals' 7-8-1 record, he would've been a legitimate MVP candidate.

This year, Johnson was aiming even higher. In the offseason, Johnson revealed that he wanted to become the third player in the NFL history to eclipse 1,000 yards as both a receiver and a runner. And Cardinals coach Bruce Arians repeatedly declared that he wanted his running back to average 30 touches per game. That kind of a historic season was only going to be possible if Johnson got good injury luck and stayed healthy. He didn't.

Hopefully, Johnson can still salvage his season by returning sooner rather than later. Before going down with the injury, he racked up 91 yards from scrimmage against the Lions.