The two tech billionaires seemingly agreed to a “cage match” face-off in late June. Zuckerberg is actually trained in mixed martial arts, and the CEO of Facebook’s parent company Meta posted about completing his first jiu jitsu tournament earlier this year.

“Zuck v Musk fight will be live-streamed on X,” Musk wrote in a post Sunday on the platform. “All proceeds will go to charity for veterans.”

Musk said earlier Sunday he was training for the fight by lifting weights.

“Don’t have time to work out, so I just bring them to work,” Musk wrote.

Whether or not Musk and Zuckerberg actually make it to the ring in Las Vegas has yet to be seen — especially as Musk often tweets about action prematurely or without following through. But even if their cage match agreement is all a joke, the banter has gained attention.

It all started when Musk, who owns X, responded to a tweet about Meta preparing to release a new Twitter rival called Threads. He took a dig about the world becoming “exclusively under Zuck’s thumb with no other options” — but then one Twitter user jokingly warned Musk of Zuckerberg’s jiu jitsu training.

“I’m up for a cage match if he is lol,” Musk wrote.

Representatives of X, Meta and Ultimate Fighting Championship, which owns the venue where the fight might take place, didn’t immediately respond to emails seeking comment.

Musk’s push to stream the video live on X comes as he aims to turn the platform into a “digital town square.” However, his much-publicized Twitter Spaces kickoff event in May with Florida Gov. Ron DeSantis announcing his run for president struggled with technical glitches and a near half-hour delay.

Musk had said the problems were due to “straining” servers because so many people were trying to listen to the audio-only event. But even at their highest, the number of listeners listed topped out at around 420,000, far from the millions of viewers that televised presidential announcements attract.