KSI has scored a split decision victory over Logan Paul in the battle of the YouTube stars in Los Angeles.
The Briton was dropped in the fourth round after Paul caught him with an uppercut - but the American landed another shot while his opponent was on the mat with the referee deducting two points.
It proved pivotal, with KSI securing a narrow win on the scorecards after six rounds of action.
A contest fought with plenty of heart but little technique was watched by millions across the planet as a fight billed as the biggest event in Internet history delivered on the hype.
With both men fighting under professional boxing rules for the first time, KSI - real name Olajide William Olatunji - was the more aggressive of the two, throwing - and missing - with a constant stream of heavy hooks that put the American under pressure.
KSI, trained by former world champion Shannon Briggs heading into the fight, tried to get his jab going and looked to swing the fight in his favour after landing an uppercut that forced his opponent to take a knee.
While KSI was still down however, Paul inexplicably continued to throw, landing a shot on the back of the Briton's head.
Paul was awarded the knockdown but docked two points - effectively costing him the fight.
KSI dashed any hopes of a third fight between the two - insisting he is "done" with Logan but suggesting he could still have a future in boxing.
Paul congratulated his rival on the win before revealing he planned to contest the decision.
"I’d love to fight KSI again - these are the best moments of my life. The more I practise in the box the more I feel comfortable," the American said.
"You’ll definitely see me in the ring again. But I am going to the commission about the decision."
On the undercard, Billy Joe Saunders marked his US debut with an underwhelming WBO super middleweight title defence against Marcelo Esteban Coceres.
The Briton laboured for much of the contest with boos coming down from the LA crowd before a thrilling finale.
Saunders produces two knockdowns in the 11th round - one a stunning uppercut that shook Coceres to his boots and while the Argentine was able to make the count, the referee stepped in to end it shortly after.
