Ryan Mathews has suffered an injury in the late Sunday night game against the Oakland Raiders, and it doesn't look good for the San Diego Chargers' starting running back.

Michael Fabiano from NFL.com reported that the reason Mathews left the game is due to what appears to be a head injury.

Ryan Mathews is on the sidelines. Broadcast speculates it could be a head injury.

— Michael Fabiano (@Michael_Fabiano) October 7, 2013

Mathews will play vs. Indianapolis