Mark Zuckerberg's intensive training in mixed martial arts didn't prepare him to face his toughest opponent - his wife.

Priscilla Chan has castigated her billionaire husband after the Facebook co-founder built an octagon ring in the backyard of their home - a possible foreshadowing of his rumored "cage match" with tech rival Elon Musk.

The new addition to the family compound did not please Chan.

"I've been working on that lawn for two years," Chan scolded her husband in an exchange of WhatsApp messages that Zuckerberg published on his Instagram account on Wednesday.

It's not clear which of the couple's 10 homes was in question. The couple have homes in Palo Alto, California, San Francisco, Lake Tahoe and Hawaii.

The tech billionaire hasn't been afraid to show off his new hobby in recent weeks.

Last month, he posted an image showing off his muscular torso as he posed alongside mixed martial arts fighters Israel Adesanya and Alex Volkanovski.

"No jokes with Mark. This is serious business," Adesanya said in the caption of the publication of three photographs, apparently referring to Zuck's potential cage fight with tech rival Elon Musk.