Elon Musk bragged about lifting '45 lb weights' on Friday. Now he says he has to get an MRI on his neck and back and may need surgery before his cage match with Zuck.

• Elon Musk said he couldn't confirm a date for his fight with Mark Zuckerberg just yet.
• Musk said he was getting an MRI of his neck and back, and might even require surgery before the fight.

Elon Musk may be set on live-streaming his fight with Mark Zuckerberg, but he wants to get his neck and upper back checked before fixing a date.

"Exact date is still in flux. I'm getting an MRI of my neck & upper back tomorrow," Musk wrote on Sunday night, responding to a tweet about Zuckerberg waiting for his confirmation to set a date for fight night.

"May require surgery before the fight can happen. Will know this week," Musk continued.

Musk's tweet about his back problems came after he announced Sunday that the fight, whenever it happens, would be streamed live on X, which was formerly known as Twitter. The billionaire added that the fight's proceeds would "go to charity for veterans."

Musk, injuries aside, has been training for his fight with Zuckerberg. In July, Canadian UFC fighter Georges St-Pierre said in a tweet that he had a "great training session" with Musk, the podcaster Lex Fridman, and the martial artist John Danaher.

And on Friday, Musk did a livestream where he lifted some weights.

"This is me curling a 45 so there you go," Musk said to the camera as he lifted a dumbbell.

Musk's video appeared to be a test for Twitter's live video feature. He later said in a tweet he was doing a quick workout while testing his products.

"Product testing & working out kills two birds with one stone! I swing one of the 45 lb weights for a kettle bell workout," Musk said, later adding in another tweet that he builds muscle fast.

Musk mentioned his neck and back issues before when he posted about a sumo match he once participated in. In March 2022, the billionaire posted a photo of himself fighting a sumo wrestler, but he did not specify when this sumo match took place.

"Managed to throw him, but it cost me smashing my c5-c6 disc & 8 years of mega back pain! Finally fixed with c5-c6 disc fusion," Musk said on Twitter, describing the back injuries he sustained during the match.

In any case, it looks as if Zuckerberg — who said he had offered Musk a date for the fight — won't be surprised by this new delay.

"I suggested Aug 26 when he first challenged, but he hasn't confirmed. Not holding my breath," Zuckerberg wrote in a post on Meta's Threads.

Representatives for X did not immediately respond to a request for comment from Insider sent outside regular business hours.