Kyle Williams will retire from the NFL after Sunday's game.

Williams has played his entire career with the Buffalo Bills as a defensive tackle after he was picked in the fifth round of the 2006 draft.

"This isn't easy. It was never going to be," Williams said in an open letter to fans posted by the Bills. "There's no perfect time to retire from a game, a franchise and a city that means so much to me and my family. But it's time to hang up my cleats."