Panthers defensive tackle Vernon Butler is expected to miss at least a month with a sprained left knee he injured during the first half of Wednesday’s exhibition victory over Houston.
Butler, the first-round pick in 2016, went down hard on a crack-back block by Texans tackle Breno Giacomini on a tunnel screen to wideout Braxton Miller.
Panthers coach Ron Rivera sent video of Giacomini’s block to the NFL for league officials to determine whether it was legal.
“That’s going to be up to the league,” Rivera said Friday. “I sent it in, just wanted to get a clarification on it. We’ll go from there.”
Butler missed five games last season with a high ankle sprain that hurt his development as a rookie.
He was in the midst of a solid training camp, but now will be sidelined for the rest of the preseason. Rivera said the team hopes Butler will be ready for the Week 1 game at San Francisco.