Gates is dealing with foot issues, nothing new for the tight end who missed six of the final eight games last season with a similar problem. The seven-time Pro Bowler also dealt with a foot injury in 2008.
Veteran Randy McMichael is likely to get the start in place of Gates.
Bob Sanders is also out for the Chargers, as expected.
For the complete list of inactives, visit http://www.nfl.com/inactives.