Oklahoma linebacker Corey Nelson will likely miss the rest of the season because of a partially torn muscle in his chest.
Sooners coach Bob Stoops says Nelson is scheduled to have surgery Tuesday for the torn pectoral.
Nelson is second on the team in tackles with 27. The senior team captain also had an interception return for a touchdown and a sack for a defense that ranks ninth in the country in yards allowed per game.
No. 12 Oklahoma plays rival Texas on Saturday with first place in the Big 12 on the line.