SAN DIEGO (AP) The San Diego Chargers placed wide receiver Stevie Johnson and nose tackle Sean Lissemore on injured reserve on Monday.

Johnson underwent season-ending surgery on his right knee after getting hurt in the training camp's second practice. Last year, Johnson, a slot receiver, had leg injuries which restricted him to 45 catches for 497 yards and three touchdowns.

Lissemore continued to have problems with his shoulders in training camp. Lissemore, who played in 11 games for the Chargers last season, was headed for a backup role with the offseason signing of Brandon Mebane.

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''This is a tough one,'' Chargers coach Mike McCoy said of Monday's roster moves. ''We are talking about two guys that they know what it means to be a pro.''

Johnson's absence means additional opportunities for Tyrell Williams and Dontrelle Inman.

With Lissemore out, a defensive line that is still minus unsigned Joey Bosa, the team's top draft pick, is getting thin. Damion Square and Ryan Carrethers will have the chance to replace Lissemore.

The Chargers also signed defensive tackle Kamal Johnson and linebackers Zack Hodges and James Vaughters. Cornerback Carrington Byndom was waived.

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