The season couldn’t have started much better for LSU.

The Tigers’ defense was outstanding, quarterback Joe Burrow was stable and Nick Brossette produced a 100-yard rushing game in the season-opening 33-17 victory against then-No. 8 Miami.

The pollsters were so impressed with the victory over the Hurricanes, whom LSU led 33-3 in the third quarter, that the Tigers leaped from No. 25 in the preseason poll to No. 11 in Tuesday’s poll. (They were as high as No. 5 on one voter’s ballot.)

But all the excitement of that good stuff was tempered by other news Tuesday – that starting edge rusher K’Lavon Chaisson will miss the rest of the season because of a knee injury suffered in the fourth quarter of Sunday’s game.

Chaisson, a sophomore from Houston, had five tackles and a sack against Miami. He was being counted on to be a major force in Dave Aranda’s defense, providing a remarkably quick pass rusher in the mold of former Tiger Arden Key.

He made the SEC All-Freshman Team last season after making 27 tackles and 2 sacks. Several teammates had said during preseason camp that they thought Chaisson had a chance to break Key’s school record of 12 sacks set in 2016.

LSU coach Ed Orgeron announced the news during his weekly news conference.

“I feel bad for him,” Orgeron said. “He’s a great young man. He’s going to get through this and will have a great career down the road.”

Shortly after Orgeron made the announcement, Chaisson reacted with a tweet:

In the meantime Orgeron and Aranda will look at a group of talented but inexperienced players to replace Chaisson.

Sophomore Andre Anthony is listed as Chaisson’s primary backup on the depth chart, but Orgeron also named sophomore Ray Thornton, junior Travez Moore and freshman Jarell Cherry as other candidates to see additional playing time to fill the void created by Chaisson’s absence.

Anthony, who’s from New Orleans, redshirted as a freshman in 2016 and missed last season because of injury.

Thornton (below), who’s from Killeen, Texas, started the final two games as a redshirt freshman last season and finished the season with 10 tackles.

Credit: Reinhold Matay-USA TODAY Sports

Moore, who’s from Bastrop, La., was a 4-star recruit coming out of Copiah Lincoln Junior College this year.

Cherry, who’s from Dallas, excelled as a sprinter in high school and was a 4-star football recruit.

All indications were that Chaisson was poised to have an impactful season, but Aranda has the tools to mitigate the loss.

The Tigers can use this week’s home opener against an FCS opponent – Southeastern Louisiana from nearby Hammond, La. – to look at each of the candidates in a game situation to better determine how to divide the reps for the SEC opener at No. 7 Auburn a week later.

The loss of Chaisson was clearly the worst news coming out of the season opener, but Orgeron said another starter will also miss time because of an injury sustained against Miami.

Starting right tackle Adrian Magee suffered a leg injury that will sideline him for two to three weeks. Magee was sharing the position with junior-college transfer Badara Traore, who filled in after Magee was injured in the first quarter.

“He was solid,” Orgeron said of Traore. “He made a couple of mistakes. We made a lot of mistakes. We looked at the film and the mistakes we made on defense, special teams on offense. But when you win, guys are going to listen. You go in in a constructive manner and fix it. Badara stepped in, showed maturity and physicality, but there things he can get fixed.”

The Tigers offensive line as a whole started poorly but played better as the game went along, gradually giving Burrow more time to operate and opening holes for Brossette, who rushed for a career-high 125 yards and scored his first two career touchdowns.