The San Diego Chargers have a running back problem.

Already without Ryan Mathews for the time being, the Chargers placed running back Danny Woodhead on season-ending injury reserve after he suffered a broken leg in Sunday’s game, head coach Mike McCoy announced Monday.

Woodhead, who fractured his fibula, is as valuable as a receiver coming out of the backfield as he is as a ball-carrier. He had 15 carries this season for 38 yards and had five receptions for 34 yards. He had 76 catches for the Chargers a year ago.

When Mathews’ knee injury was diagnosed on Sept. 15, it was anticipated that he would be sidelined four to five weeks, so he will miss a few more games.

It means Donald Brown probably will have a heavy workload for the next few weeks. Brown has carried the ball 40 times for 81 yards this season and has eight catches for 37 yards.

In Sunday’s victory over Buffalo, Brown had 31 carries for 62 yards and five receptions for 37 yards.

The Chargers may have to sign a running back to add depth at the position.