TAMPA, Fla. (AP) -- Rookie Kwon Alexander has done more than create a good first impression in training camp with the Tampa Bay Buccaneers. The fourth- round draft pick of out of LSU has played his way into the starting middle linebacker job.

The regular-season opener is more than three weeks away, however, coach Lovie Smith already has seen enough of Alexander to move him ahead of veteran Bruce Carter on the depth chart.

Carter had five interceptions as an outside linebacker with the Dallas Cowboys in 2014. The Bucs signed him in free agency with expectations that the fifth-year pro would be able to make a smooth transition to the middle.

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Smith said moving Alexander into the starting defense after the rookie's strong performance in the preseason opener at Minnesota is more a reflection of how the rookie is playing rather than any dissatisfaction with Carter, who's now competing with Danny Lansanah for the starting spot at strongside linebacker.

"What happens when you make plays? You get an opportunity to get more plays," the coach said.

Alexander played 32 snaps against the Vikings on Saturday night, finishing with four tackles. He began working with the first team defense when practice resumed this week.

It didn't take the young linebacker long to show why the Bucs feel like he has a promising future, forcing a fumble during an 11-on-11 drill and scooping up the loose ball before running back Charles Sims could react.

"He's there because we feel like he can make plays like that. ... I think every day you are going to see him doing something better," Smith said. "He has big play ability."

Alexander, who turned 21 on the third day of camp, is also playing with a bit of chip on his shoulder. He left LSU after his junior season, expecting to be drafted earlier than the fourth round and is determined to prove he's better than that.

At the same time, he's trying to keep his promotion to starter in perspective.

"It's a blessing just to be with the ones. It's my dream. I wanted to come up here and start," Alexander said. "I'm still trying to start, because the (final) decision is not made. I'm just out here working, trying to grind and get better and better every day."

Alexander was an all-SEC selection last season and decided to turn pro with one year of eligibility remaining to pursue a goal he's had since growing up in Oxford, Alabama, where he was rated the second-best high school prospect in Alabama behind Jameis Winston, now a fellow rookie with the Buccaneers.

"Me and Kwon have known each other since our sophomore year, just because Alabama kids know each other. That's definitely a football state," Winston said. "He's an amazing player. Back then, he was a little skinnier just like me, but he always was able to fly to the ball and make great plays."

The 6-foot-1, 227-pound Alexander considers himself a good fit for Tampa Bay's defense. The Bucs say he's a good athlete who's shown he's a dependable tackler who also has the potential to excel in pass coverage.

The rookie has worked both inside and outside in camp and believes he's capable of playing either position.

"Wherever coach wants me to play, I'm going to play. But the middle is harder because you're the key of the defense. You've got to call everything out so everybody knows their roles," Alexander said.

Defensive coordinator Leslie Frazier has been impressed with how Alexander studies and prepares.

"From the point that we put pads on, we've improvement all the way through," Frazier said, adding the rookie's versatility will help the Bucs.

"The thing that's impressed us is his ability to play man coverage. He's not just a guy who can drop in zone," Frazier added. "We think we will be able to match him up sometimes on tight ends and running backs as well. That's always a plus the way people spread you out today in the NFL."

If Alexander remains atop the depth chart, he could be one of four rookies starting for Tampa Bay when the regular season opens against Tennessee.

Winston, the No. 1 overall pick in the draft, won the quarterback job even before taking a snap in training camp. Second-round selections Donovan Smith and Ali Marpet are projected starters on the offensive line.

Smith isn't fazed by the prospect of having to depend on young players at key positions.

"It's just left to us as coaches to stimulate that process of catching them up," Smith said.

"If you are the best guy, it doesn't matter if you are a rookie or whatever, we'll play you right away," the coach added. "But you have to do that a little bit for people to believe it. I think the guys believe it around here."