A 12-year-old American football who went viral had to prove his age after nobody believed him.

Jeremiah Johnson from Fort Worth, Texas, became an internet sensation after collecting the U12 MVP honours at the Youth National Championships in Miami, Florida.

He possesses a hulking physique, a moustache that Steve Harvey would have been proud of and appears to have a number tattoos on his right arm.

One man posted a video where he asked Johnson how old he was and he responded by politely saying, “I’m 12.”

The reaction to him was off the scale and Tyreek Hill, wide receiver for the Miami Dolphins, was astonished by what he saw.

Accompanied by a laugh emoji, he tweeted: "If that 12 year old really 12 my son not playing football, these kids built different."

But Johnson had to address the claims he wasn't actually 12 and went on the Talk’R Media Network podcast, with the host asking him: “A lot of people say you don’t look your age. Does that make you feel a certain type of way? What’s your opinion on that?”

Johnson replied: “I know I don't look like my age. I mean, it doesn’t really affect me.”

He also confirmed that the tattoo that he was seen on his arm was a fake, temporary one. But he also had to let everyone know that there was "no truth" to claims his birth certificate said 1989 on it.

He also addressed the fact that he has a seriously strong bit of facial hair that people a lot older would be proud of, adding, "When I was six, I started growing a moustache".