David Montgomery was running all over the Detroit Lions before exiting the game with a knee injury in Week 4. Now, the Chicago Bears have clarity on the injury and how long their starting running back will be out for.

Montgomery had run for 106 yards and two touchdowns for the Bears against Detroit before the injury. His absence is a crucial one for Chicago as they try to pile up some wins early on in the season.

The good news for the Bears is that the injury isn't season-ending, as some had initially feared. The bad news is four to five weeks is still a large chunk of the season to be without your star back.

Chicago will likely turn to Damien Williams with Montgomery out and they also made another corresponding move to add depth to the position.

The move to bring back Artavis Pierce appears to be a depth move more than it is a move to have Pierce become the focal point of the backfield with Montgomery out. Williams is dealing with a thigh bruise but initial reports have indicated he should be fine and good to go in Week 5 for the Bears.

Chicago stands at 2-2 and they are one game back of the Green Bay Packers in the NFC North. The road ahead doesn't get easier for the Bears as a date with the 3-1 Las Vegas Raiders in Vegas awaits Chicago in Week 5. They will host the Packers the following week in Chicago.