MINNEAPOLIS — No fire burned hotter, no mouth was fouler, no opponent was in for a longer night than Kevin Garnett’s.

In more than two decades in the NBA, Garnett opened the door for a new wave of young talent to enter the league, was partly responsible for a rewriting of the collective bargaining agreement and nearly singlehandedly redefined what the game’s tallest players were allowed to do on the court.

Fittingly, and maybe a little reluctantly, No. 21 is calling it a career after 21 years, leaving a legacy as one of the best defensive players in league history and one of the game’s most influential and intense competitors.

Garnett posted a video on his Instagram account on Friday, saying “farewell” and “thank you for the journey.” He narrated the short, black-and-white video that shows him walking alone through Target Center with sunglasses on.

“I’m just thankful. I can’t even put that into words,” Garnett says. “I’m just thankful. I’m just thankful for everybody and the love. I never would have thought that people love me like this. But, for it to be reality is just something else, man. Man.”

Garnett informed the Timberwolves of his decision to retire Friday. The team will waive the franchise icon, which will allow him to collect his entire $8 million salary for next season. That is the same approach the San Antonio Spurs took with Tim Duncan.

“I’m proud of our association with Kevin, just seeing him grow over the years,” Wolves owner Glen Taylor told The Associated Press. “I wish him the very best in the future and want to thank him, along with our fans, for the great memories that he has given us.”

The 15-time All-Star was MVP in 2004 after leading the Timberwolves to the Western Conference finals and ranks first in the league in career defensive rebounds, third in minutes played and fifth in games played.

“Kevin Garnett is one of the fiercest competitors our league has ever seen,” NBA Commissioner Adam Silver said in a statement released by the league. “He held himself to the highest standard of preparation and performance for a remarkable 21 seasons. On behalf of the NBA family, I thank Kevin for his sustained excellence and the enormous impact he’s had on the game.”

The 40-year-old Garnett put the Timberwolves on the map by turning one of the most hapless franchises in professional sports into a perennial playoff team. He later helped return the Boston Celtics to glory, winning a championship in 2008. And he did it all with an unmatched competitive drive that made him a renowned terror in practices and versatile dynamo in games.

“Everything changed the day Kevin arrived in Boston,” Celtics co-owner Wyc Grousbeck said. “From that moment we knew we would get to the Finals and have a chance to win. I’ve never met such a relentless competitor or such a great teammate. I’m so proud he will always be a Celtic champion.

He came into the league straight from high school in 1995, the first player to do so in 20 years. The move paved the way for Kobe Bryant, LeBron James and Tracy McGrady to follow him, and for the league to institute a rule requiring players to be one year removed from high school before being draft eligible. Garnett also made more than $330 million in his career, the most by any player in league history, and owners dug their heels in during a lengthy lockout in 1997 after a 21-year-old Garnett signed a six-year, $126 million deal.

To his teammates and coaches, he was worth every penny.

He was unyielding on the court, bumping his head on the basketball support while muttering to himself and working up a sweaty lather before the opening tip. One of his trademark moves was to block the shot of an opposing player who tried to get a freebie after a foul was called. The message was clear: nothing was going to be easy with him prowling the paint.

Garnett insisted on being listed at 6-foot-11 even though he was at least two inches taller. He didn’t want to be pigeon-holed as a big man that needed to stay around the basket when he was so much more. Known as the “Big Ticket,” Garnett could handle the ball, shoot it from outside, take an opponent off the dribble and guard all five positions.

“He literally changed our culture,” said Clippers coach Doc Rivers, who coached Garnett in Boston. “You look at all the things he stands for. He follows through on all of them.”

That razor’s edge could cut deep. Garnett is famous for eviscerating teammates who he thought were going through the motions in practice and opponents would get furious at the sneaky elbows and moving screens KG would pull while battling for rebounds.

He spent a forgettable season and a half with the Brooklyn Nets before the late Flip Saunders convinced Garnett to agree to a trade to return to Minnesota at the deadline in 2015.

During his second stint with the Wolves, he served as a mentor to youngsters like Karl-Anthony Towns, Andrew Wiggins, Gorgui Dieng and Zach LaVine, instilling in them a sense of intensity and professionalism that helped lay the foundation for what the team hopes is a breakout year for the upcoming season.

“You know how much I’m gonna miss playing with you and just simply having you around,” Towns wrote on Instagram . “Congrats on having one of the greatest careers the game has ever seen. We talked. I know what I must do. I’ll take it from here.”

Garnett spoke often of his desire to one day get into ownership with the Wolves, but it remains unclear if that is still possible after Saunders’ passing. The Wolves have new basketball leadership in coach/president Tom Thibodeau and GM Scott Layden, and Garnett has little sway in the organization now that Saunders and previous coach Sam Mitchell are gone.

“That would be a lot up to him,” Taylor said. “Things have changed so much and does he still want to do that? We certainly will have the opportunity to talk about that. There’s a lot of good reasons to do it and I’m open to it.”

Garnett had contemplated returning for a 22nd season, which no player has ever done. But knee issues limited him to just 85 games over the last two seasons, and after Saunders died from Hodgkin’s lymphoma before last season, he lost the man he trusted most in the organization.

“We going to be all right, man,” Garnett says in the video. “I don’t expect this to be easy. But so far so good. Stay tuned.”