Outside linebacker Jadeveon Clowney, who had already been declared out of Sunday's game with Baltimore, will now miss at least the next three games as the Titans placed him on injured reserve with a knee injury.
Clowney did not practice all week and missed the game two weeks ago against Chicago before returning in the Titans' Thursday night game against Indianapolis last week.
With Clowney out, the Titans will likely go with Derick Roberson to start alongside Harold Landry at outside linebacker.
In a corresponding move, the Titans promoted defensive back Greg Mabin from the practice squad to the active roster. The Titans also placed defensive back Kareem Orr on injured reserve.
In addition to that, safety Kenny Vaccaro, who had been questionable with a neck injury, was downgraded to out with a concussion and will not play, leaving Amani Hooker likely to start alongside Kevin Byard.
The Titans already had declared cornerback Adoree' Jackson, receiver Adam Humphries, guard Rodger Saffold, defensive lineman Larrell Murchison and tight end MyCole Pruitt out for the game.
The Titans chose inside linebacker Will Compton and outside linebacker Tuzar Skipper as their practice squad promotions for the game against the Ravens. Long snapper Matt Overton was also added for the game.