The single is the first to be taken from her new album 'Roar'
Pop banger will now be available to download from September – a week earlier than originally planned
Fans can hear 30-second clips of 'Dark Horse' and 'Walking On Air'
Icona Pop and Iggy Azalea will support at September 30 date
Chart battle sees Perry lead sales by 2:1 in the US
Moombahton producer says singer copied his video...
Meanwhile, Perry's new single 'Roar' has leaked ahead of its planned premiere later today (August 12)
Track is the first to be taken from her forthcoming new album 'Prism'
US pop singer reveals album title and release date on giant gold truck
Keith Hudson has also asked people to 'pray' for his daughter
Jahmene Douglas rules out performing 'Last Friday Night'
'Teenage Dream' singer will play at the Nokia Theater in Los Angeles on October 7
'Firework' singer and Australian cricketer Doug Bollinger distracted exam students with saucy dance moves, claims lawyer
The singer's spinning peppermint bra is declared a safety hazard by tour insurers
Singer's new film is trounced by 'The Amazing Spider-Man' according to box office figures
Singer says she wants to give artists a chance at financial success
The pop singer is apparently keen to play Mary Austin alongside Sacha Baron Cohen in new Queen film
Mel B, Anastasia, Nicole Scherzinger and Sharon Osbourne also in the running to replace Kelly Rowland
Couple photographed hand in hand at Coachella
Singer also reveals that she almost landed a role in an Oscar-winning movie