Brandon Harris said he doesn’t get nervous.

We’ll see.

Harris, a true freshman from Bossier City, will start in No. 15 LSU’s game at No. 5 Auburn on Saturday night, coach Les Miles announced Monday.

Miles is replacing a struggling Anthony Jennings with a gunslinging, dual-threat rookie who wowed fans in Saturday’s win over New Mexico State.

A backup for the first month of the season, Harris is poised to be the first true freshman to start at quarterback this early in the season — the sixth game — in more than 22 years (Jamie Howard in 1992). He’ll be the first true freshman to start at the position in the regular season since Jordan Jefferson in 2008.

Miles said he came to the decision after watching a replay of last Saturday’s game — one that include multiple missteps from Jennings and multiple touchdowns from Harris.

“I don’t think it was a difficult decision,” the coach flatly said Monday.

Harris out-dueled Jennings in the 63-7 win, entering the game in the second quarter and leading the Tigers (4-1, 0-1 Southeastern Conference) to touchdowns on his seven drives. Jennings played the first seven possessions of the game. LSU’s offense scored once, and Jennings threw two interceptions and lost a fumble as fans serenaded him with a chorus of boos multiple times.

Meanwhile, a rowdy student section chanted, “We want Bran-don!”

Harris was named SEC Freshman of the Week by the league Monday, a good day all around for a guy who has impressed in his No. 2 role this year.

A highly touted recruit out of Parkway High, Harris has thrown 30 passes this season, completing 22 for 394 yards and six touchdowns. Going back to the 34-29 loss against Mississippi State, he’s led LSU to touchdowns on nine of his past 10 series.

“There’s some ad-lib to his game that’s very positive,” Miles said. “He’s a guy who really is fast and can really throw the ball. If you put him in a quality position to extend a play, and some good things can happen.”

That said, much of his playing time has come against lower-level squads or with LSU up big or down big.

He now gets the starting nod against the reigning SEC champions, Auburn (4-0, 1-0), at Jordan-Hare Stadium. Under second-year coach Gus Malzahn, Auburn is 11-0 at home.

“I never get nervous in situations like that,” Harris said after the win Saturday. “My body language may say I’m nervous, but I just never get nervous.”

That will be tested in front of 87,000-plus fans on the Plains in a nationally televised game with tremendous implications on the SEC West race. A sidebar to the affair: Harris chose LSU over Auburn and Ohio State last year.

“He’ll be ready,” defensive tackle Christian LaCouture said of Harris. “No doubt about that.”

Harris was not made available to reporters Monday.

Players said they heard the quarterback news only after Miles told a group of reporters at his weekly press conference Monday. LaCouture and teammates were relaxing in the players’ lounge when the news drifted in about 2 p.m.

“Excited for the kid,” LaCouture said. “Brandon’s a guy that really works his tail off and gets the job done.”

The quarterback change opens a new piece to what’s been a somewhat dry offense. Already, LSU’s offense is beginning to morph from a tight-end heavy, I-formation unit to one that spreads the field and aligns in the shotgun.

In a blowout win Saturday, LSU used a two-tight-end set just four times in Harris’ 40-plus snaps. He was in the shotgun on about half of those plays, and the Tigers offense switched to a more up-tempo attack with the speedy freshman behind center.

Miles pushes aside talk of Harris changing LSU’s offense. Running back Terrence Magee didn’t.

“The package when (Harris) gets in is always a little bit different than Anthony runs,” Magee said. “When he gets in, it’s always a little more up-tempo because we’re trying to catch them moving around and not in position.”

A change in the offense is one of many things Harris brings.

He throws a smoother and harder pass, players have said. His pocket presence and decision-making appear to be stronger than anything Jennings has shown.

National pundits noticed the difference between the two players.

The color analyst in Saturday’s game, former Georgia offensive lineman Matt Stinchcomb, said during the broadcast about the pair of quarterbacks: “Such a stark contrast that there’s really not much of a comparison.”

Miles’ decision may end a seventh-month-old quarterback battle.

Harris enrolled early in January and immediately began competing with Jennings for the No. 1 job. He wowed spectators at the Tigers’ spring game but lost the starting gig during a back-and-forth battle with Jennings in August.

Harris got three snaps in the first half in the season-opening win over Wisconsin and then saw nothing but mop-up duty over the next two games — blowout wins over Sam Houston State and Louisiana-Monroe.

A turning point came in a home loss to Mississippi State.

He entered for an injured Jennings with 3:43 left and LSU down 34-16. He threw for 140 yards and two touchdowns in the final four minutes, nearly helping the Tigers pull off an improbable comeback.

He followed that last Saturday by marching the Tigers down the field for scoring drives of 80, 62, 70, 3, 75, 74 and 65 yards.

Up next: Auburn.

“We have to get a win,” Harris said. “It’s a must-win game.”

Follow Ross Dellenger on Twitter @DellengerAdv. For more coverage of LSU football, follow our Tiger Tracks blog at http://blogs.theadvocate.com/tigertracks/.