The Dutch dance duo — 'aided' by the Far East Movement' — knock will.i.am and Britney Spears down to Number 2, while Taylor Swift climbs to Number 3 with 'I Knew You Were Trouble'.
Elsewhere in the Top 10, manchild Conor Maynard climbs 28 places to Number 6 with 'Animal' while poor ignored Emeli Sandé somehow earns another hit single as 'Clown' climbs three places to Number 8.
It's not great news for Amelia Lily whose second single 'Shut Up (And Give Me Whatever You Got)' enters at Number 11, while Little Mix's empowerment anthem, 'Change Your Life', is new at 36.
On the album chart, the Les Misérables soundtrack thing holds tight at Number One for a second week, while Calvin, Rihanna, Ed Sheeran, Bruno Mars, One Direction and Fun. all climb within the Top 10.