The 10-year-old schoolboy from North Canberra, who is also a member of Mensa, received standing ovations for his performances on Australia's Got Talent earlier this year, and made it all the way to the grand final.

The show's judge Kelly Osbourne was a huge fan of Callum's, having praised him, "a pure genius rock star".

Kelly told an astounded Callum that her father would "100 per cent" see his performances and later confirmed that Ozzy had indeed witnessed the 10-year-old's guitar-playing and "he was in shock and he couldn't believe it".

With Ozzy touring the country with Black Sabbath this month there had been talk of Callum meeting the heavy metal legend.

The McPhie family didn't get confirmation until lunchtime Friday that it was all going ahead the very next day, and they would be going to Black Sabbath's Sydney show.

"We get the ultimate package for the three of us which is a sound check, a meet and greet with the band, then the show and I think they're talking about some time with Ozzy after that as well – so we're absolutely ecstatic," says Callum's dad, Doug McPhie.

Since the grand final, Callum's made waves internationally, and has been written about in heavy metal magazines in 16 different languages. Instead of getting hundreds of views, his YouTube videos now garner tens of thousands.

But at the end of the day, Callum's just like any other 10-year-old, enjoying his school holidays.

"He's having a play date today and running around in the backyard. For him it's just another day being a kid," said Doug.

"For us it's an incredible thing because we know how few and far these sort of things come along. For him over the last seven months a lot of these things have come along. He's just like 'this is what you do isn't it, you jump around on your trampoline then you go and meet Ozzy Osbourne'."