Oklahoma defensive tackle Charles Walker has been ruled out of playing in Saturday's game against the Texas due to a concussion he suffered in last Saturday's win over TCU, Sooners coach Bob Stoops said Wednesday.

Walker also sat out last season's College Football Playoff semifinal against Clemson after suffering a concussion in practice leading up to the game.

Walker was rated the No. 20 prospect for the 2017 NFL draft, according to ESPN Insider Todd McShay.

He has seven tackles this season, including two for loss.