Chargers' Ryan Mathews carted off with knee injury vs. Seahawks

San Diego Chargers running back Ryan Mathews left Sunday's game in the fourth quarter on a cart. 

Mathews suffered an apparent knee injury and is questionable to return.

The Chargers will need Mathews back as soon as possible, as they face off against a surprisingly tough Bills' run defense in Week 3. 

Mathews ran for 1,255 yards last season and added six touchdowns. It should be noted that it was his first complete season, as he has missed time with varying injuries throughout his career.

The fifth-year pro ran for 31 yards on 11 carries against the Seahawks.