A gay fan's elaborate marriage proposal has helped land Australian pop star Betty Who a support slot on Katy Perry's Prism world tour.

The 23-year-old singer, real name Jessica Newham, became an overnight Internet sensation in the U.S. last year (13) when devotee Spencer Stout used her song Somebody Loves You as the soundtrack to a flashmob video he made to ask his boyfriend Dustin Reeser to marry him.

The video was posted on YouTube.com and came to the attention of Perry and her managers, who have since decided to invite Betty Who to join the pop superstar on tour when she arrives in Australia later this year (Nov14).

The singer tells the Sydney Daily Telegraph, "No one had any idea that video would go totally insane viral. The boys found my song on Spotify and both loved and it has been the most beautiful thing to be a part of."

Betty Who will have more of a musical pedigree than the headliner when she tours with Perry - a prodigy, she moved to Michigan to study cello at the Interlochen Centre for the Arts. She also attended Berklee College Of Music in Massachusetts.

But she cannot wait to join Perry on tour, adding, "I was in a van with the band and my manager says, 'You have just been chosen to open for Katy Perry. In Australia.' Everyone went silent - that’s how you know something has totally blown me away."