Thomas sat out Wednesday and Thursday with a knee injury, but he expects to play.
"Taking a day off was just a matter of trying to make sure I was as fresh as possible on Sunday for the speed guys in Seattle," Thomas, who hasn’t missed an offensive play since the Browns drafted him third overall in 2007, said Thursday.
Gilbert practiced for the first time since suffering a concussion Nov. 30 against the Baltimore Ravens. He missed two games with the injury.
Kicker Travis Coons (groin) attended practice, though he didn't kick during the period open to reporters.