Oregon's Thibodeaux leaves opener with ankle sprain
"He got rolled up on," coach Mario Cristobal said postgame, according to 247 Sports' Matt Prehm. "Beyond that, I know it's a sprain. We're very optimistic it's nothing serious.
"Kayvon's injury was certainly something you don't want to see happen for anybody. It hurts us considerably on the edge."
The Ducks held off Fresno State 31-24 to pick up a win in its season-opening contest.
Thibodeaux wore street clothes and a walking boot while on the sidelines following halftime, according to The Athletic's Bruce Feldman.
Before leaving the game early, Thibodeaux produced a sack and forced a fumble on the same play.
The sophomore defender entered the 2021 campaign with high expectations after recording 38 tackles, 9.5 tackles for loss, and three sacks across seven contests last season.
The California native was named the Pac-12 Defensive Freshman of the Year in 2019.
Thibodeaux is considered one of the top prospects eligible for the 2022 NFL Draft.
Oregon returns to action on Sept. 11 against Ohio State.