Texans left tackle Duane Brown left practice Wednesday with a lower leg injury.
"He got rolled up, kind of got hit on the outside of his leg," said coach Gary Kubiak. "It's part of football, unfortunately. We'll hold our breath. Hopefully, he's OK."
Brown walked off the field and applied ice to his ankle but was taken to the locker room on a cart and then for tests on what the team believes is an ankle injury. Rashad Butler, who was competing for the starting right tackle job in light of the offseason departure of Eric Winston, moved to left tackle after Brown's injury on Wednesday.
"In my opinion, Duane molded himself into the best left tackle in the game," quarterback Matt Schaub told the Houston Chronicle. "... I never have to worry about Duane because I know he's going to get the job done."
Brown gave up 2.5 sacks last season and is arguably the team's top blocker.
Butler started four games at left tackle in 2010, when Brown was suspended for a violation of the NFL's substance-abuse policy.
Brown was a first-round pick from Virginia Tech in 2008. He's in the final year of his original $9.1 million rookie contract.