Russia’s undefeated former UFC Lightweight Champion Khabib Nurmagomedov refused to train Tesla's Elon Musk, the current world's richest man, over a "matter of principle," TASS reported on Monday citing members of Khabib's team.

Musk's request came after SpaceX's CEO agreed to hold a live-streamed MMA fight with Meta's owner and American billionaire Mark Zuckerberg.

"Khabib’s refusal was a matter of principle," the source said. "He has wrapped up his coaching and sports career and nothing can change this. Musk’s [present-day] status plays no role at all."

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"However, Khabib keeps receiving proposals on a regular basis to be a coach or make a comeback," the source noted. "But this is impossible."

"Khabib declined [Musk’s] proposal and we do not know the reasons [for his refusal]," a source informed on the matter told the Russian news agency.

The fighting match, which comes within the framework of the UFC, will reportedly be held either at the MMA octagon in Las Vegas or as Musk suggested at Italy's Roman Colosseum.

In 2020, the 34-year-old Russian fighter retired from professional fighting after successfully defending his title through a 29 consecutive win streak. Since then, he has committed to coaching his friends and teammates.

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