KSI almost PASSED OUT from exhaustion while training to fight Tommy Fury.
The YouTube, music and boxing star faces Fury in a massive celebrity bout on Saturday in Manchester.
And KSI lived up to his workaholic reputation in camp for the grudge match having been pushed to his absolute limit.
In a clip from a pre-fight documentary, the Londoner is put through his paces on a versaclimber machine – a climbing-style workout.
His head trainer Alexis Demetriades barks encouragement and counts down as KSI tirelessly works.
After the round is over, the unbeaten social media sensation almost collapses into Demetriades’ arms.
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Somehow, KSI then gets back on the machine for one final round of brutality.
As he works away, Demetriades says: “Every single professional fighter in this gym, you need to beat them.”
Fury, 24, comes into the fight having beaten KSI’s arch rival Jake Paul, 26, by split-decision in February.
Whereas KSI, 30, last fought in May where he accidentally but illegally knocked out businessman-turned boxer Joe Fournier, 40, with an elbow.
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But he snubbed a rematch to instead focus on outdoing Paul by attempting to beat Fury.
KSI’s coaches are so committed to preparing him to the max they offered sparring partners bonus money to KO him.
Demetriades said: “From where he was at when he first came to where he is now, he’s come on leaps and bounds.
“He’s only sparring professional boxers, this whole camp, forget MMA fighters, forget amateurs.
“He’s sparring guys 14-0, 13-0, 12-2, 8-0, 6-0, all with knockouts and all ranked by the British Boxing Board of Control.
“If they think that we’re not taking this seriously, we’ve got guys who are ranked higher than Tommy Fury in the gym.
“And they’re not just moving around, they’re trying to kill JJ and there’s bonus money on the table for them to knock him out.
“From a coaching point of view, all I want to do is put the correct guys in front on KSI and see whether or not he can deal with that and if he can’t then he shouldn’t be fighting.”
Source: Boxing - thesun.co.uk