JACKSONVILLE – Paul Posluszny has been ruled out of Sunday's game.
Posluszny, the Jaguars' starting middle linebacker and leading tackler, was downgraded from questionable to out on Saturday, a day before the Jaguars' game against the Arizona Cardinals at EverBank Field.
Posluszny, who was named the AFC's Defensive Player of the Week for his performance in the Jaguars' victory over Tennessee last Sunday, sustained a concussion with 2:11 remaining in that game. He did not practice Wednesday, Thursday or Friday and was ruled out Saturday.
Russell Allen, the Jaguars' starting strong-side linebacker, will start for Posluszny, with rookie John Lotulelei making his first NFL start at strong-side linebacker.
Posluszny never has missed a game since signing with the Jaguars before the 2011 season.