Dwayne 'The Rock ' Johnson Welcomes Muhammad Ali to Instagram

To welcome the boxer to Instagram, the actor told a story about his "hero."

— -- Muhammad Ali joined Instagram today, and so far, he's only followed one person: Dwayne "the Rock" Johnson.

According to the actor, the two have had a bond that spans nearly 40 years.

"I first met my hero and friend, Muhammad Ali when I was 6yrs old in New Zealand. He pretended to spar with me and pulled me up on his lap to take this pic," Johnson wrote on Instagram, along with the photo below. "In that moment, his kindness made me the happiest kid in the world."

Johnson, now 42, added that 12 years passed before they met again, but Ali remembered him.

"He pulled me in for a hug and whispered, 'Can you rumble?,'" Johnson wrote. "In 1998, as The Rock in the WWE, he granted me the true honor of using his title, 'The People's Champ' - a title I proudly carry for life."

After encouraging his more than 5 million followers to follow Ali, Johnson concluded by thanking the legendary boxer for his kindness: "Welcome to Instagram champ! #ThankUForBeingSoKindToMeAsAKid #NeverForgotIt #NothingIsImpossible #YouAreTrulyThePeoplesChamp"