Simon Cowell has warned fans of new global superstar Susan Boyle not to get too carried away by the Britain's Got Talent sensation's success.

The unemployed 47-year-old - who says she's "never been kissed" - has quickly become a worldwide hit, with a Youtube clip that has notched up in excess of 15 million clicks, and a host of A-list followers including Demi Moore and Twitter king Ashton Kutcher.

Susan even made her US television debut on Good Morning America (see clip below.)

But Simon doesn't think we should write off the rest of the competition just yet.

He says: "I think we've got to treat it as it is, which is a competition. There are some other acts you haven't seen yet.

“It's not quite the one horse race you're going to think it is."

Way to go to rain on Susan's parade, Simon...