Anthony Smith's place among the elite light heavyweights in the world is secure.

"Lionheart" went into Alexander Gustafsson's hometown and finished him via rear-naked choke submission at 2:38 of the fourth round Saturday in the main event of UFC Stockholm. It was the biggest win of Smith's 11-year career and arguably his best performance.

Afterward, Gustafsson took his gloves off and left them in the Octagon. He confirmed after the fight that he would be retiring.

"The show is over, guys," Gustafsson said. "... It feels like I don't have it anymore. I have done it for a long time. I'm 32 years old, I have kids, built the life that I wanted thanks to this sport. It feels like I'm getting old. We all have to realize that it's the end of the story."

Smith controlled the majority of the fight. He got the better of the first two rounds with a series of hard left hooks. Gustafsson seemed content to stay on the outside and wait for the action to come to him.

In the third, Gustafsson found his rhythm. The leg kicks he had been throwing began adding up, he landed a hard jab that got Smith's attention and then hurt Smith with a body kick before landing a takedown.

Smith said he broke his left hand earlier in the bout and was trying to work around it. He said in the fourth round he started to adjust.

"I decided to figure it out," Smith said. "I tried to throw a couple of hard body shots after that. I felt [my hand] swelling in my glove. I think a little of it was panic."

Smith took Gustafsson's back in a wild scramble after a Gustafsson takedown attempt failed in the fourth. He managed to flatten Gustafsson out, land ground and pound and cinch in a rear-naked choke for the finish. Smith reminded everyone afterward that he was a Brazilian jiu-jitsu black belt.

Smith (31-14), like Gustafsson, was coming off a loss in a title fight to Jon Jones. This was the Nebraska native's 12th career submission win. Smith, 30, has the most finishes in the light heavyweight division since 2018 with four. He'll keep his top-five ranking.

Gustafsson (18-6) has lost two straight and four of his last six, but all of his opponents have been the very best in the division. He has fought three times for the UFC light heavyweight title and gave Jones the toughest fight of his career in 2013.

Gustafsson has been the best Swedish fighter in the UFC and the promotion's top draw in the country.

"I'm very disappointed," Gustafsson said. "It happened again, I lost in my own home. You know what, it's a sport; it's hard. You do it because you love it.

"... I never did this for the money or anything like that. I did it because I want to be the best, and if I can't be the best, then it is what it is. Now, I'll focus on my kids, I own a gym and have a couple of other projects going on. Let's see what is the next chapter."