Katy Perry and Lady Gaga, two of the undisputed queens of modern pop music, have both released a new single this week in the US and early estimates are showing that - perhaps somewhat surprisingly - Perry is streets ahead of her rival in sales figures.

Perry's latest effort 'Roar' is predicted to shift somewhere in the region of 550,00 units, according to Billboard, making it the biggest first week of sales in her career thus far. Perry's previous personal best was the 509,000 sales of 'Part of Me' in December of 2010.

Lady Gaga, on the other hand, has released a new track 'Applause' and, despite the music video featuring a scantily clad Gaga (are we sensing a theme here lately?) it's understood that the best Gaga can hope for is sales somewhere around the 225,000 mark.

You can listen to the two tracks here, which do you prefer?