An emotional Khabib Nurmagomedov struggled to hold back the tears after beating Justin Gaethje at UFC 254 in Abu Dhabi on Saturday evening.
The 32-year-old forced Gaethje to tap out with a triangle choke submission in the second round.
He then announced his retirement in his post-fight interview inside the Octagon, to the shock of UFC fans.
Khabib, who bows out with a flawless 29-0 record, said: "It was my last fight. There's no way I'm going to come here without my father. It was the first time after what happened with my father, when the UFC called me about (fighting) Justin, I talked with my mother for three days.
"She didn't want me to fight without father, but I promised her it was going to be my last fight, and if I give my word, I have to follow this. It was my last fight here.
"I know only one thing I want from the UFC: Tuesday, you guys have to put me number one pound-for-pound fighter in the world because I deserve this.
"Undisputed UFC lightweight champion, 13-0, 13 in the UFC, 29 in my pro MMA career. I think I deserve this."
Gaethje, meanwhile, was incredibly gracious in defeat.
Despite the fact he’d just tapped out, the 31-year-old American consoled his emotional opponent on the canvas. He also applauded when Khabib, whose father Abdulmanap died in July following complications caused by Covid-19, was announced as the winner.
Asked by BT Sport what he said to Khabib, Gaethje revealed: “I said ‘I haven’t had a chance to tell you that I’m so sorry for your loss - but you just made your father really proud’.”
Absolute class. Fair play, Justin.
“Right now [the defeat] hurts,” he admitted. “There’s not a lot of people that can make me feel better, this is on me. I need to go home and deal with this on my own because you step in there [the Octagon] alone.
“I have a lot of comforting voices and I know that I’ve made so many people proud just by stepping in and being ready. The preparation I put in is second to none and people appreciate that. That’s what they’re fans of me for: for how hard I work and how I carry myself. I’m just here to make people proud and on to the next one.”
Khabib also paid tribute to Gaethje with his post-fight victory speech.
"Thank you so much Justin,” he said. “In 2016 I remember, when I cut weight, you helped me a lot. Thank you brother.
"I know you're a great man and I know how you take care of your close people.
"I know lots of things about you.
"Be close to your parents because one day it's going to happen.
"You never know what's going to happen tomorrow, you never know."
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