Ahead of their boxing match on August 25, Deji, younger brother of KSI, showed up to the training gym of his opponent Jake Paul, and was immediately slapped as the pair came face to face.
Jake, younger brother of Logan Paul, is the main undercard for the KSI vs Logan bout, fighting Deji (a.k.a ComedyShortsGamer), and the tension between the two seems to be increasingly real.
Initially, speculation was that animosity between the two was somewhat manufactured, invented to stir up anticipation for the fight, selling more tickets and pay-per-view.
But, Jake Paul seems to genuinely dislike Deji, if his recent actions are anything to go by. Deji posted the following clip on Twitter, showing Jake Paul take a 'cheap shot', slapping him.
"Cheap shot by Jake the bitch Paul"
It seemed to be an entirely unmotivated attack, with Jake seemingly surprised by Deji's appearance, and instantly wanted to skip any talking and get to the point.
Jake tweeted about the incident, saying Deji had turned up unannounced and to "talk shit", so Jake slapped him and a video would be coming soon.
Deji responded, writing "You had to cheap shot me, you hit like a bitch."
Another angle, from a camera in the crowd's perspective, shows Jake slap Deji unexpectedly, prompting his opponent to lash out in retaliation, but the entourage from both sides quickly stepped in.
Logan Paul also reacted to the slap on social media, unsurprisingly backing his younger brother for "slapping the shit out of [Deji]".
Regardless of how Deji feels about the cheap shot, it is a stunt that will only heighten the anticipation for an already long awaited fight on August 25.
The main event is of course the older brothers, KSI vs Logan, but Deji and Jake Paul are big names on YouTube in their own right, and fans will be equally intrigued to see who comes out on top in that one too.
You can watch the fight live on the official KSI vs Logan Paul YouTube channel, but it is a pay-per-view live event, costing £7.50 to purchase access. It takes place at the Manchester Arena, UK, and is expected to pull in a sell out crowd.