Elon Musk expressed his concerns for Kanye West because "there seems to be a lot of issues".
Concerns for the rapper, 43, have been snowballing on social media and among the Kardashian clan after a Twitter firestorm where he appeared to end his marriage with Kim Kardashian, 39.
Kanye has since issued a public grovelling apology to his wife after she stood by him and said her husband was "brilliant yet complicated" because he suffered with bipolar.
At the time, his friend and space engineer, 49, fired off a text to the musician mid-way through his twitter rampage to check on if he was OK.
Although Elon said Kanye "seemed fine on the call", he suspected things were "not fine" and "there seem to be a lot of issues".
He said: "When he was about a third of the way through the tweet rampage, just to see if he was doing OK, I sent him a text saying, you know, 'Just checking on you, a lot of people are worried, just wondering if you're OK'.
"He seemed fine on the call. But it sounds like things are, you know, not fine. There seem to be a lot of issues."
Having backed Kanye's presidency bid from the beginning, the SpaceX CEO tried to persuade his long-time friend to run for president in 2024 rather than 2020.
Previously, Elon told Kanye he had his "full support" while running for president.
He added to The New York Times : "I've done my best to convince him that 2024 would be better than 2020."
Their friendship goes back to at least 2011.
So it's no wonder Elon had been advising Kanye with his 2020 run for president.
Elon has had his own Twitter rampages in recent weeks.
The billionaire got the attention of his girlfriend Grimes when he posted a rant starting with: "Pronouns suck."
He was hit with a backlash after many Twitter users believed the outspoken star was attacking the trans community.
His girlfriend Grimes, and mother of his baby X AE A-Xii, urged her other half to turn off his phone.
She wrote: "I love you but please turn off ur phone or give me a dall [sic].
"I cannot support this hate. Please stop this. I know this is not your heart."