Sheikh Jassim is ready to take legal action against new Manchester United co-owner Sir Jim Ratcliffe.
The pair competed for control of United last year before a revised offer of taking a minority shareholding in the club won the day for Ratcliffe.
The English billionaire would later quip, "I'm not sure he exists," when asked about the Qatari - a joke that has not gone down well with Sheikh Jassim.
The Athletic says the words of Ratcliffe has seen the Sheikh gather his legal entourage together.
It's reported via his legal team Sheikh Jassim has complained about 'a pattern of demonstrably false and defamatory' statements from Ratcliffe.
Furthermore, the Qatari is believed to demand immediate corrective action from the new United co-owner.