This was already a big week for Donnie Alexander.

When No. 25 LSU travels to play No. 22 Texas A&M on Thanksgiving night, the Tigers junior linebacker will play against a team that employs the coach who recruited him, John Chavis, and a receiver who’s one of his best friends, Speedy Noil.  

The week just got a lot bigger.

Starting middle linebacker Kendell Beckwith will miss the game at A&M on Thursday night, interim coach Ed Orgeron announced Monday, and Alexander is expected to start in his place, players said.

“I’m not just a backup anymore,” Alexander said. “I’m on the front lines.”

Beckwith, the Southeastern Conference’s second-leading tackler, twisted the knee late in the first quarter of the loss to Florida. His status for a possible bowl game is uncertain. The injury comes eight months after he sprained the medial collateral ligament in the same knee during spring practice.

This one at least appeared more serious. Beckwith spent several minutes writhing on the field at Tiger Stadium while trainers huddled around the senior from Clinton. He walked off on his own power, lightly putting pressure on the knee.

He spent the rest of the game watching from the sideline and coaching up his replacement, Alexander.

“He just told me to stay focused and play my game,” Alexander said during an interview Monday.

Beckwith is arguably one of LSU’s most indispensable players. In a fit of odd timing, the 6-foot-3, 250-pounder was named Monday as one of five finalists for the Butkus Award, given annually to college football’s top linebacker. He’s projected as a second- to third-round NFL draft pick and was invited last week to the Senior Bowl.

He leads LSU with 91 tackles, 10 more than the next-best player and second only to Vanderbilt linebacker Zach Cunningham’s 109.

The task in replacing Beckwith is made more difficult based on LSU’s past in recruiting linebackers. Coincidentally, the Tigers on Thursday face the man who was partly responsible for recruiting said linebackers. Chavis served as LSU’s defensive coordinator and linebackers coach in 2009-2014.

The Tigers signed two linebackers in two signing class, 2014 and 2015, and just one of them, Alexander, remains on the team. They’re missing a big, hulking backup to Beckwith. That guy was supposed to be Clifton Garrett, a five-star signee from Illinois who transferred after his freshman season.

LSU signed no linebackers in 2015, when, a month before signing day, Chavis left the program for the Aggies.

Mike Scarborough, publisher of TigerBait.com, the Rivals.com affiliate covering LSU, said he believes part of Chavis and then-defensive line coach Brick Haley’s departures regarded their recruiting.

“That’s part of the reason why Chavis and Brick Haley aren’t there anymore,” he said for a story that ran in the spring. “It’s not all on them either. Coaches don’t just recruit their positions. They have territories.”

Orgeron and staff have no other choice but to play a 215-pounder in place of the bulky Beckwith. Alexander laughed at the thought of reaching Beckwith’s weight through a mad eating binge over the next few days.

“He’s a big guy. I can gain 10 in a week. Don’t know about 35,” he laughed.

Gaining weight is an offseason focus for Alexander, a player who’s expected to be the third in a line of athletic, shifty linebackers who needed three years of seasoning before starting as seniors: Deion Jones and current linebacker Duke Riley.

“I soaked everything up from them and tried to put it in my game,” he said.

Freshman Devin White, listed at 255 pounds, could see action as well Thursday, but the rookie from North Webster appears to be well behind any others. He’s played sparingly in games this year, rarely seeing more than one significant series a game on defense.

Still, they all must be ready to replace someone so essential to one of the nation’s best defenses.

“I know Kendell is a big loss for the defense,” Alexander said. “I want to go out there and make it seem like he’s still there in a type of way.”

Against Florida, LSU felt his absence over the final three quarters. The Gators ran for 20 yards on nine carries, a 2.2-yard average, before Beckwith’s injury. They ran for 106 yards on 26 carries, a 4.8-yard average, against a Beckwith-less LSU defense.

Florida’s 15-play, 70-yard march in the fourth quarter included 13 runs, many of them straight at the heart of a unit missing its big guy in the middle. 

It’s another blow for defensive coordinator Dave Aranda’s group, a unit that's allowed a nation-low 11 touchdowns in 10 games. Beckwith is the fourth starter to go down with a serious injury this year. He joins tackle Christian LaCouture (knee, preseason camp); outside linebacker Corey Thompson (leg, preseason camp); and safety Rickey Jefferson (leg, after Game 5).

“It’s been a rough one,” said John Battle, who replaced Jefferson at safety. “As I had to step up, somebody else will step up. Donnie did a good job on Saturday. I expect him to have a big game Thursday.”

It was already big for this former Edna Karr product.

Chavis recruited, signed and, at least for one season, coached Alexander.

Noil, A&M’s fourth-leading receiver with 16 catches and 223 yards, is one of his best buds. The two played together at Karr and are still close. They spoke as recently as two weeks ago, Alexander.

They’re competitive, too. They might not be matched up against one another, but Alexander plans to hunt down his old friend before the game and during.

“If I can catch him,” Alexander said, “I’m going to put something on him.”

Follow Ross Dellenger on Twitter, @RossDellenger.