|KSI v Logan Paul II|
|Venue: Staples Center, Los Angeles Date: Saturday, 9 November (Sunday, 10 November UK time) BBC coverage: Live radio commentary on BBC Sounds and live text commentary on the BBC Sport website and app.|
Most professional boxers will begin their careers in front of a handful of people at obscure leisure centres. KSI and Logan Paul are not most professional boxers.
On Saturday night, the YouTubers - combined following 40 million - will fight in front of an expected sell-out crowd of 21,000 at the Staples Center in Los Angeles, USA. Millions more will watch on pay-per view television.
It is not the first time they have fought - their first contest, at Manchester Arena in August 2018, ended in a draw.
Promoter Eddie Hearn is among those who believe the rematch is a huge opportunity for the sport of boxing, though others are less convinced.
Here Hearn, pundit Steve Bunce and fighter-turned-trainer Jamie Moore answer the question: what does KSI v Logan Paul II mean for boxing?
A new audience, a new opportunity
It was reported Britain's KSI, 26, could have earned more than £80m from his first fight with American Paul. As well as the 15,000 fans ringside, more than a million watched on YouTube.
In comparison, British heavyweight Tyson Fury signed a five-fight deal reportedly worth the same figure earlier this year.
KSI and Paul have turned professional for this bout, which is being promoted by Hearn's Matchroom Boxing.
Hearn, who promotes the likes of British former world champion Anthony Joshua, said he simply "couldn't ignore" the success of the first fight.
"I watched it and thought I should be involved with it," he said. "The YouTube world is a remarkable way of people digesting content and it fascinates me.
"There will be a huge, new audience worldwide and it's our job to make sure they take an interest in boxing - then they buy tickets and watch other fighters."
BBC boxing pundit Steve Bunce had reservations about the fight initially, but now sees the opportunity for the sport.
"If 10% of their followers watch the fight, that's four million new sets of eyes on the sport," he said. "Even if we took just 1%, that's still an enormous number."
'They're better than hundreds of other debutants'
KSI and Paul are taking this fight seriously. Both have regularly uploaded training videos to social media to show the progress they have made.
Turning professional means they will box without head guards, with smaller 10oz gloves - which include less padding than those used in amateur contests - and over six three-minute rounds.
And Bunce has been impressed with what he has seen so far.
"They have trained for two months and stopped everything else they do to fight each other," he said.
"They've changed their shape, their lifestyle and they're devoted.
"I've had serious arguments with people in this business because I have pointed out there are fighters who have had debuts and are absolutely hopeless - and these two, I think, are better than hundreds of those."
What can boxers learn from KSI and Paul?
Londoner KSI first rose to fame when he uploaded a clip of a goal he scored on computer game Fifa. Paul, meanwhile, came to prominence on social media platform Vine.
Bunce believes there is a lot boxers can learn from social media celebrities about the art of self-promotion.
"If I was a promoter, I'd get my fighters to look at how these guys and girls are doing it on YouTube or Facebook," he said.
"If you think boxing shouldn't be influenced by the online community, are you living in 1979? We're in 2019. Get with it."
They're 'not just here for a pay cheque'
Both KSI - whose real name is Olajide William 'JJ' Olatunji - and Paul have been criticised for their often bizarre outbursts and trash-talking in the build-up to the fight.
Those who attended the London and Los Angeles news conferences heard jokes about dead dogs, and references to World War Two and Sir Winston Churchill.
Hearn admits their behaviour has been "a little bit cringey" at times, but says the way they conduct themselves is the reason they have such a big following.
And the criticism does not seem to bother either fighter.
"I'm going to use boxing IQ and show everyone that I've put in the work and I'm not here for a pay cheque," KSI told the Mayweather Channel.
Paul, meanwhile, told BBC Newsbeat boxing is "by far one of the best things to happen" in his life.
So why are some boxing traditionalists against it?
Hearn - who says he has no plans to stage celebrity fights in the future - acknowledges "hardcore" boxing fans may not be happy with his involvement in this fight.
"I do respect what they know about boxing, but I can't take advice from them on something like this," he said.
Moore, meanwhile, is pleased both fighters will make "loads of money" but thinks it should not be considered a professional bout.
"It's not really boxing - it's two young men who have a bit of a problem with each other and are using boxing to sort their beef out," said the former British champion.
Moore, who now trains former world champion Carl Frampton, acknowledges the work both men have put in, but says it is easier to train for a one-off fight than try to forge a career in boxing.
"It's a short window of time where they have to put their bodies through hell - but they know the end of goal is that they will definitely be earning a lot of money," he said.
"Young professional fighters have no idea what the end goal is."
Should it be the headline?
Some criticism of the fight has centred on the fact it will headline a bill also featuring British undefeated WBO super-middleweight world champion Billy Joe Saunders and American WBC lightweight champion Devin Haney.
Moore feels an established fighter should be headlining an event of this magnitude.
"As a world champion, Billy should absolutely be topping the bill," he said.
But others argue this is a smart move by Matchroom and will give much-needed exposure to Saunders, who does not have a big profile in the United States.
"I'm far from insulted," Saunders told IFL TV. "If I can nick maybe 5,000 new fans then financially it's a pretty good bill to be on."