Alexander Gustafsson explains why he's retiring after UFC Fight Night: Gustafsson vs. Smith. For more UFC on ESPN+, sign up at http://plus.espn.com/ufc. (0:34)

Gustafsson: 'It feels like I don't have it in me anymore' (0:34)

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.

"The show is over, guys," Gustafsson, 32, said.

He confirmed after the fight that he will retire.

"It feels like I don't have it in me anymore, to be honest," Gustafsson said. "It feels like I do mistakes that I shouldn't, so I just have the feeling it's the time now. I don't want be a journeyman. I don't want to do this because I'm getting paid. I just want to do this because I love it and I want to be at the top."

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 round, 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.

Gustafsson By The Numbers 1 -- Of 11 light heavyweights to win 10-plus fights

1 -- Only fighter in UFC history to land 100-plus strikes in two title fights and lose both (Jon Jones, Daniel Cormier)

4 -- Fight of the Night bonuses in his UFC career

9 -- Knockdowns in light heavyweight fights, 4th-most in division history

-- Finishes with career record of 18-6 (10-6 in UFC)

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 round. 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.

play 0:34 Gustafsson: 'It feels like I don't have it in me anymore' Alexander Gustafsson explains why he's retiring after UFC Fight Night: Gustafsson vs. Smith. For more UFC on ESPN+, sign up at http://plus.espn.com/ufc.

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.

Jones took to social media after Saturday's fight ended.

Honestly I don't believe you but if you're serious, thank you for everything. You held the division to a standard and made us better. Go kick ass with that Family. — Jon Bones Jones (@JonnyBones) June 1, 2019

"[I'll miss] that feeling of getting your hand raised," Gustafsson said. "It's hard to explain with words, you have to do it to understand the feeling of a 'W.' That's what drives me ... being there and [winning]. You're the king of the world. Nobody can stop you. It doesn't matter what check you get in your hand. It doesn't matter what people say or talk. It's you and you're the f---ing king of the world when you're standing there."

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," he added later. "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."