Britney Spears' fiance debunks video claiming they met when he was a childhood fan

Britney Spears and Sam Asghari. Photo / Instagram

Britney Spears' fiance Sam Asghari has debunked a wild rumour that he first met her at an autograph signing when he was a childhood fan more than 20 years ago.

Personal trainer Asghari, 27, shared footage that has been circulating on social media showing a teenage Britney in 2000 gushing adoringly over a young boy at an autograph signing.

"You want a picture with me? I just want to pinch you! Will you call me when you're older? You promise? Please!" Spears tells the youngster, pulling him onto her lap for a photo.

It'd make for a jaw-dropping origin story for the pair, who sparked up a romance after Asghari appeared in the 2016 music video for Spears' single Slumber Party and announced their engagement earlier this month – but it's too good to be true.

"Just want to clear things out. This is not me. I had facial hair I was 6'2" and spoke five different languages at this age," Asghari jokingly captioned the video.

In a follow-up post to his Instagram stories, he delivered more proof: a childhood photo of him and the young boy side-by-side.

Britney Spears and a young fan (not her future fiance). Photo / Supplied

Asghari has previously opened up about what it was like to first meet Spears on the 2016 video shoot where he was playing her love interest.

"I was excited that I (would) get to meet one of the biggest artists of all time," Asghari told Men's Health in 2018. "I had butterflies."

At left, a young Britney fan and at right, a young Sam Asghari. Photo / Supplied

But things got off to a bad start when Asghari tried to make a joke which failed spectacularly.

"She said, 'Hi, I'm Britney,' and I said, 'I'm sorry, what's your name again?'" he recalled. "I tried to be funny. I don't think anybody got it."

Spears announced on Instagram on September 13 that she and Asghari were finally engaged after four years together. She shared a sweet video of the two of them together and captioned the post: "I can't f***ing believe it."

Britney Spears and Sam Asghari. Photo / Instagram

The engagement news comes in what is a busy month for Spears: Next week sees the release of a highly anticipated new Netflix documentary investigating the 13-year conservatorship arrangement she has lived under, and has publicly railed against recently.

The next court hearing for the conservatorship is set for September 30.