The pair's Scream & Shout lands at number one, and I Knew You Were Trouble by Taylor Swift, who is also coming off a bad break-up from One Direction hunk Harry Styles - jumps to two.
James Arthur's Impossible falls to three, Rihanna climbs to four with Stay, and Drinking from the Bottle by Calvin Harris and Tinie Tempah is in fifth.
Meanwhile, David Bowie's new Where Are We Now, which was released on his 66th birthday, debuts at number six, his first top 10 single in 20 years.
In the U.K. albums chart, Emeli Sande's Our Version of Events reclaims the top spot, trading places with Calvin Harris, whose 18 Months drops to two.
Jake Bugg's self-titled album is at three, Rihanna's Unapologetic lands at four, and the Les Miserable soundtrack enters at five.
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