The Carolina Panthers expect to be without backup quarterback Sam Darnold for an extended period of time with what coach Matt Rhule described as a "significant" high ankle sprain suffered in Friday night's preseason finale against the Buffalo Bills.

The typical recovery time is four to six weeks. 

"It is a significant injury that could take some time," Rhule said Saturday. "If it's at least a four-game injury, we can put him on the short-term injured reserve."