Tommy Fury beat Jake Paul by split decision in Saudi Arabia on Sunday, declaring that he had made his own "legacy" while also leaving open the possibility of a rematch with the YouTuber-turned-boxer.
Briton Fury, the half-brother of WBC heavyweight champion Tyson Fury, took a standing eight count in the eighth and final round of the cruiserweight contest at Diriyah Arena but was still awarded the bout 76-73 on two judges' scorecards with one judge giving Paul the fight 75-74.
Addressing the crowd through tears afterwards, Fury said: “For the past two-and-a-half years this has consumed my life but tonight I secured my own legacy. This is a world title for me.
“This was my first main event. I will come back bigger and better and stronger, if he wants the rematch he can bring it on.”
Paul, who calls himself "The Problem Child", drew loud boos with his post-fight claim that he "got sick really bad twice in this camp" and "injured my arm", though he added he was "not making excuses".
He told reporters that Fury had "impressive combinations" but that the loss was "a reflection of my own performance".
"I couldn't get my momentum going like I wanted to and I just felt kind of flat," he said.
A triumphant Fury, for his part, boasted that he "showed everybody that I ain't scared of no one and I can cut it in the big dance."
Paul first gained fame and millions of followers on the now-defunct social media platform Vine and also YouTube before pivoting to boxing about five years ago.
His 6-0 record heading into Sunday's fight, including four knockouts, had come against a ragtag group of opponents that included another YouTuber and three mixed martial arts fighters.
He was out to bolster his credibility against Fury, who was likewise undefeated, though his past opponents were also hardly household names.
Fury, who was defending an undefeated 8-0 professional record, will controversially earn a place in the WBC cruiserweight rankings.
It will also prove a lucrative evening’s work for Fury after his father John accepted Cleveland-born Paul’s double-or-nothing offer at Thursday’s pre-fight press conference.
Paul was penalised a point for holding in the fifth round, with British fighter Fury also facing a deduction in the next.
It was the first defeat of Paul's career having entered the bout unbeaten in six fights.
In the co-main event challenger Badou Jack put on a clinical display of boxing, stopping Ilunga Makabu in the 12th and final round to win the WBC cruiserweight title, the third weight class in which the 39-year-old Swede has held a world title.
Jack downed Makabu with a big right hand in the fourth round and decked him again in a similar manner in the 11th, and though South African Makabu's undoubted power posed a threat until late in the fight, he eventually capitulated.
With his corner telling him ahead of the final round that he needed a knockout to win, Makabu came out swinging, but Jack's crisp combinations overcame him, forcing the referee to step in and stop the fight as the Swede claimed the belt.
Saudi fighters Ziyad Almaayouf, who made his professional debut at "Rage on the Red Sea", and Ragad Al Naimi, the kingdom's first female professional boxer, were both victorious in undercard matches on Sunday.