The Ravens announced that slot cornerback Ar'Darius Washington has been placed on injured reserve with a chest injury.

It's unclear when Washington suffered the injury. He played 95 percent of the Ravens' defensive snaps on Sunday and showed no indications of being hurt, and Ravens coach John Harbaugh said on Monday that the Ravens weren't putting anyone on injured reserve.

Baltimore's secondary is dealing with other injuries, as cornerback Marlon Humphrey is recovering from foot surgery and safety Marcus Williams is recovering from a pectoral injury. Arthur Maulet, who has been inactive so far this season, will probably take Washington's place at slot corner.

To take Washington's spot on the roster, the Ravens signed center Sam Mustipher to the 53-player roster. Mustipher played in the first two games as a practice squad call-up but is now on the regular roster.