He suffered the injury in Alabama's 65-31 win over Arkansas on Saturday.
It's another blow for an Alabama secondary that has dealt with a number of physical issues this year, including season-ending injuries to corner Jalyn Armour-Davis and safety Daniel Wright.
Losing Diggs—the younger brother of Minnesota Vikings star wide receiver Stefon Diggs—is particularly tough, however, as he was in the middle of an excellent season, posting 20 tackles and an interception. In his stead, true freshman Patrick Surtain II is likely to step into the starting lineup.
Saivion Smith could also see his role expand.
"We're obviously very thin and need some guys to step up and develop," Saban said, per Alex Scarborough of ESPN.com. "But Patrick has played quite a bit at his position. We do have two guys that have some experience, but we don't have a lot of depth right now.
The Crimson Tide (6-0) haven't been challenged yet this season, beating every opponent thus far by at least 22 points. They are the frontrunners to win yet another national championship, though they could be facing a test on Saturday in a Missouri team averaging 39 points and 530 yards per game.
Without Diggs, Missouri quarterback Drew Lock—and every opponent to follow—will likely test Alabama's secondary early and often. How they respond will be crucial for the Crimson Tide's title hopes.