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LSU linebacker Arden Key (49) shows his excitement coming out on the field for pregame warmups as LSU head coach Ed Orgeron, left, checks on his other squads during the first half of LSU's football game against Auburn Saturday Oct. 14, 2017, in Baton Rouge, La.. LSU won 27-23.

KNOXVILLE, Tenn. — Two starting members of LSU’s front seven did not make the trip for the game against Tennessee.

Edge rusher Arden Key and inside linebacker Donnie Alexander, both battling injuries, are not available for Saturday night’s game at Neyland Stadium, multiple sources confirmed to The Advocate. Their absence thrusts two true freshmen back into starting roles: Tyler Taylor, for Alexander, and K’Lavon Chaisson, for Key.

Key and Alexander sustained injuries in last Saturday’s win over Arkansas. Key injured his knee late in the first quarter; he played the next two quarters before leaving early in the fourth quarter. Alexander injured his shoulder or neck in the first half but finished the game. Neither player was spotted at practice Monday through Wednesday.

Their absence is significant.

Key, a junior, is projected as a top 25 pick in the NFL draft next year, set the school’s single-season sack record in 2016 and has four sacks and 33 tackles this season.

Alexander is fourth on the team with 49 tackles in what has been a rocky senior season. He missed the game against Ole Miss with a neck injury, according to teammate Devin White, and missed the season opener while presumably on suspension. He was also suspended for the first half of the game against Syracuse after a targeting call the week before at Mississippi State.

The extent of their injuries is not known, and coach Ed Orgeron sidestepped a question Thursday night about Key’s longterm health. LSU (7-3, 4-2 Southeastern Conference) hosts Texas A&M in the regular-season finale next Saturday.

This will be Taylor’s fourth start. The Georgia native often rotates with Alexander, playing anywhere from two to four drives per game when Alexander has started.

Chaisson, a Houston native and like Taylor a highly ranked prospect in the 2017 signing class, filled in for Key in the first two games of the season while the former All-American recovered from May shoulder surgery. Chaisson’s rotation time has diminished significantly since the beginning of the season, as Key has gotten into game shape. Chaisson normally plays in two to three drives per game.

“They’ve played before. Started them before. Those guys have done a good job,” LSU coach Ed Orgeron said Thursday evening about Taylor and Chaisson. “They’re young guys going to play hard. We feel like they’re physically capable of handling the situation and know they are going to still make mistakes. Got to be patient with them.”

Playing freshmen is nothing new for Orgeron this season.

The Tigers have played 20 of them, and eight have started at least one game, the most for LSU since 2005. Three of those are regular starters: safety Grant Delpit and offensive linemen Saahdiq Charles and Ed Ingram. Chaisson, Taylor and F-back Tory Carter are regular rotational freshmen.

Several freshmen have seen their playing time drop over the season, none more than Texas product Kary Vincent. He began the season as a starter at the team’s nickelback position before the staff moved Donte Jackson into that role. Playing time for defensive end Neil Farrell has dropped, too, as veterans grow healthier on the defensive line.

Orgeron met with the freshmen a few weeks ago for a discussion regarding their progress, he said Thursday night.

“Here’s what we see with most of the freshmen: We’ve seen them progress, seen them hit a wall, because they weren’t getting as much playing time, and then we’ve seen them bounce back. Typical freshmen,” the coach said.

“I met with the freshman group two or three weeks ago about what I expect of them. Some of them were doing it and some weren’t, and they’ve picked it up since. They’re a good group, just need guidance and coaching every day.”

Follow Ross Dellenger on Twitter, @RossDellenger.