Alabama defensive signal-caller Dylan Moses likely will miss the 2019 season, sources told ESPN, after the inside linebacker suffered a knee injury during practice Tuesday.

Crimson Tide coach Nick Saban said on the SEC media teleconference that Moses will need surgery on the knee and will be out "indefinitely."

"Certainly, this is a character check for our team, and we're going to do everything to support Dylan and the people that have the opportunity now to fill in for Dylan," Saban said.

Moses, a Butkus Award finalist last season, finished with 86 total tackles -- 10 for loss -- and 3.5 sacks in 2018.

He was ranked No. 13 on the preseason Big Board by ESPN NFL draft analyst Mel Kiper Jr.

Saban told ESPN earlier this month that linebacker was among the thinnest positions on the team and that the Tide could ill afford to have injuries there this season.

Alabama was already dealing with the loss of senior inside linebacker Joshua McMillon, who suffered what's believed to be a season-ending knee injury earlier this month.

"We can't afford to lose a lot of guys on defense, especially at linebacker," Saban said then. "We haven't been able to stay healthy there the last few seasons, and that's limited some of what we've been able to do on defense. We've got good players, but a lot of young ones, too. The maturity level, knowledge, confidence and experience -- it's going to be a little bit of a work in progress to get it where we need it to be."

With McMillon and Moses sidelined, the Tide defense will lack experience at inside linebacker.

Saban said Wednesday that true freshman Shane Lee was the backup to Moses at middle linebacker and "he's the guy that will have the opportunity to play now."

Sophomore Markail Benton, who had 14 tackles last season, also is listed as a backup to Moses on the official Alabama depth chart, which was released Monday.

Christian Harris, another true freshman, is listed as a starter at the second inside linebacker position.

"We try to get these guys prepared every day," Saban said of the backups. "They know they're only one play away from having to be in the game. Fortunately, for the guys that we have as backup linebackers, they have been good students of the game, and they've really tried to prepare themselves the right way."

Alabama opens the season against Duke in Atlanta on Saturday.