South Korean pop sensation Psy has vowed to perform his dance anthem Gangnam Style topless if the hit reaches the top of the U.S. pop charts.

The star's catchy tune is on the rise and on course for number one - and when it gets there, fans are in for a treat.

He says, "If it ranks number one in the Billboard chart, then I will perform Gangnam Style topless in a place where everyone can watch."