Two of the world tech industry’s top billionaires, Elon Musk and Mark Zuckerberg, apparently want to go beyond their business rivalry and settle scores in a “cage fight.”

Twitter owner and Tesla CEO Musk recently tweeted that he would be “up for a cage fight” with Zuckerberg, the CEO of Meta, the parent company of Facebook.

In an Instagram story on Wednesday, Zuckerberg accepted the challenge by posting a screenshot of Musk’s tweet with the caption: “Send Me Location.”

Musk then responded to a tweet about the fight by Alex Heath, editor of tech news website Verge, with “Vegas Octagon” which is a reference to the Las Vegas arena that hosts the Ultimate Fighting Championship.

“I have this great move that I call ‘The Walrus,’ where I just lie on top of my opponent & do nothing,” he added in a separate tweet.

He later tweeted short videos of walruses, which perhaps indicates that his challenge to Zuckerberg may not be serious.

CNN has contacted Meta for comment. A spokesperson for the company told Verge: “The [Instagram] story speaks for itself.”

It remains unclear whether Zuckerberg and Musk are serious or just joking around. However, Zuckerberg is a martial arts expert and has recently participated in a competition.

The two have clashed on social media before.