Francis Ngannou made a triumphant return to mixed martial arts with a first-round stoppage of Renan Ferreira at the PFL Super Fights event in Riyadh, Saudi Arabia.
Cameroon's Ngannou knocked out Ferreira with some brutal ground strikes in his first MMA contest in nearly three years.
The 38-year-old shed tears as he dedicated the victory to his late 15-month-old son Kobe, who passed away earlier this year.
"I can't think about anything [other] than my son Kobe. I only took this fight because of him," said Ngannou.
"I went to fight for him. I hope they can remember his name because without Kobe, we wouldn't be here tonight. I wouldn't have fought."
Since leaving the UFC as its heavyweight champion 22 months ago, Ngannou has become one of the world's biggest combat sports stars following blockbuster boxing bouts against Tyson Fury and Anthony Joshua.
But he has been adamant in the build-up to this encounter that he "never left MMA", and always planned to fight again in the cage.
Ngannou considered retirement earlier this year, but said he had chosen to fight on in memory of Kobe as a way of "honouring him".
The fight was Ngannou's PFL debut and the organisation took advantage of the money their biggest star now generates by building the card around him and creating commemorative 'Super Fight belts'.
Announced as the "one true heavyweight MMA champion" in reference to his being stripped of his UFC title after leaving the promotion early last year, Ngannou opened a contest billed as 'the Battle of the Giants' with a leg kick, wobbling Ferreira.
Ferreira, the PFL's 2023 global league heavyweight champion, responded with a leg kick of his own, but would soon find himself on the back foot as Ngannou secured a takedown.
After defending a triangle choke attempt, Ngannou took control, posturing up and launching a series of ground strikes down on a helpless Ferreira.
With the Brazilian not defending himself, the referee stopped the contest as an emotional Ngannou crouched against the cage, gathering his thoughts in victory.
"I knew I didn't miss a step. I wasn't worried about it because as soon as I walked in the gym I knew everything was still there," said Ngannou.
"It was just me being able to manage my emotions. Deal with life separately, not mix things up. That's what I have been working on.
"I think my next move in combat sports all depends on me, how I feel. I always think I have a lot to give and I keep thinking that way."
The card was typical of recent big sporting events to take place in Saudi Arabia, with a glamorous opening ceremony.
National flags of each fighter competing were paraded to the cage, ending with the Saudi Arabian national anthem, as global stars such as Portuguese footballer Cristiano Ronaldo watched.
