Derek Lokey will undergo surgery later this week for the broken fibula he suffered in the Longhorns' 22-20 win over Nebraska on Saturday.
Lokey had four tackles in the game at the time he was injured and has 24 tackles (12 solo), four tackles for loss, a half sack, nine QB pressures and a fumble recovery on the year.
In a release from UT Longhorns head coach Mack Brown said of the injury:
"This is an unfortunate setback for Derek and our defense. He has established himself as one of the key contributors to our defensive front and as one of the leaders in that group. It will be important that someone steps up and fill his void for us to continue to be one of the best defenses in the country."