SAN DIEGO (CBS) – The San Diego Chargers may have defeated the Green Bay Packers on Thursday night in the preseason opener, but lost running back Ryan Matthews to injury.

Matthews, on his first run attempt of the preseason, suffered a broken clavicle that will put him out four to six weeks; Bill Johnston of the San Diego Chargers confirmed the injury.

Matthews was expected to be a major part of the Chargers offense this season, as well as a valuable running back in fantasy leagues. Now, Matthews must overcome yet another injury in what has been an injury-prone career thus far.

In Matthews’ absence, third-year running back Curtis Brinkley had 11 carries for 42 yards and a touchdown. Brinkley and Michael Hayes, an undrafted rookie free-agent signee, received the bulk of carries for the remainder of the game. Ronnie Brown could be the starter for week 1 if Mathews isn’t able to go