It's being called one of the most exciting chart battles in recent pop history.
New singles from US pop divas Katy Perry and Lady Gaga are set to battle for the No. 1 spot on this week's Billboard Hot 100 chart, currently occupied by Robin Thicke's Blurred Lines.
Perry's Roar and Gaga's Applause were both leaked on Aug 10 and instantly started a paws-versus-claws war among their fan bases, the KatyCats and Little Monsters.
It got serious enough for Gaga to step in at one point and beg for peace, tweeting: "Let's make 2013 a year where music/talent/artistry is more important than gossip/fanwars I respect all fanbases 4 their passion #BeTheChange".
But the fan wars were just the start of a flurry of Perry-versus-Gaga drama.Both critics and fans have weighed in, and overwhelmingly the winner seems to be Perry, whose single has been praised as being pure pop perfection while Applause has been derided for not living up to the hype.
Though Roar has been beset by plagiarism accusations, the song was projected to sell 525,000 downloads by the end of last week, according to Billboard.
In comparison, Billboard projected Applause - from Gaga's upcoming album Artpop - to sell less than half that number. No wonder then that Gaga's feeling the pressure.
After the leak of Applause, she took to Twitter to dangle this to the Little Monsters - buy her single and stand a chance to meet her in person.