SAN DIEGO - San Diego Chargers centre Rich Ohrnberger has been placed on season-ending injured reserve with a back injury that will require surgery.

He is the third Chargers centre to go on IR this season, following Nick Hardwick and Doug Legursky.

Ohrnberger started seven of the eight games he played this season.

Last Sunday, rookie Chris Watt became the fourth Chargers player to start at centre this season.

The Chargers filled the open roster spot by signing outside linebacker Cordarro Law from the practice squad.

___

Online: http://pro32.ap.org/poll and http://twitter.com/AP_NFL