LSU safety Rickey Jefferson expected an increased role this season.

He’ll definitely have one now — at least through the first two games of LSU’s season.

Starting safety Jalen Mills suffered an injury to his ankle during the morning session of practice Wednesday, sidelining him for at least the first two games of the year, his mother told The Advocate.

It thrusts Jefferson into a starting role while sending Mills to the bench — a rarity. Mills has played all 39 games of his LSU career.

The extent of Mills’ injury isn’t known, but Kisa Mills said her son won’t need surgery and classified the injury as a “sprain.” It will sideline him for the season opener Sept. 5 against McNeese State and the game at Mississippi State the next week.

“He will be OK,” Kisa Mills said in a message Wednesday.

An X-ray result to Mills’ ankle on Wednesday night returned positive results, a source said. The hope is for Mills to return by the third game of the season, LSU’s highly anticipated showdown in Tiger Stadium against Auburn, a source said.

After the Auburn game, the Tigers travel to Syracuse and host Eastern Michigan in the lightest two-week stretch of the year. Mills’ return could be put off until the game at South Carolina on Oct. 10.

Mills suffered the injury during a team drill, the Tigers’ final day of two-a-days and the official break of preseason camp. Another player rolled onto Mills’ ankle, two sources said.

School spokesman Michael Bonnette would only confirm that Mills suffered an ankle injury during morning drills. At a scheduled player interview session Wednesday night, many players talked openly about Mills’ injury.

“It’s tough,” said Jamal Adams, the projected starting safety opposite Mills. “We’re going to bounce back, and he’s going to be fine. He’s going to be right there in the mix with us by midseason or whenever he comes back.”

“We were hurt. We went (into the training room) to console our brother while we could,” Jefferson said. “He was at low spirits, but he has his spirits pretty high right now. He’ll be back sooner than later.”

Jefferson is expected to replace Mills — something he already did often last season. In the Tigers’ five-defensive back set, Mills moved from safety to nickel back, and Jefferson replaced him at safety.

The Tigers play nickel — the five-defensive back set — just as much, or more, as their base 4-3 defense in some games. Dwayne Thomas is the most likely candidate to replace Mills as nickel back.

Thomas and Jefferson have big shoes to fill.

Mills, a DeSoto, Texas, native, has never missed a start in his three-year career. He moved from cornerback to safety as a sophomore in 2013 and played there all last season, rolling up 62 tackles.

The injury is a costly one, but it comes at a position group that’s one of the squad’s deepest and most talented.

“I think in the back end we have so much depth and so much talent,” Adams said. “Rickey Jefferson, he stepped right in and no letdown.”

Adams and cornerback Tre’Davious White are preseason All-Southeastern Conference players. There is an ongoing battle at the other cornerback spot between Thomas, highly touted freshman Kevin Toliver and sophomore Ed Paris.

Corey Thompson, a starter in 2013 who missed last season while recovering from a knee injury, said Wednesday he’s fully healthy and is playing safety. Jefferson’s backup is sophomore John Battle.

“I feel like I was going to play a lot this upcoming year anyway,” Jefferson said, “but it definitely gives me an opportunity to play more.”

Players rushed to console Mills following the injury.

“Gave him hugs and prayed for him,” Jefferson said. “When a situation like that happens, it’s very sad, but you’ve got to try to keep his head up and know that everything is going to be all right.”

Follow Ross Dellenger on Twitter @DellengerAdv.