The track, Pillowtalk, achieved combined sales of 112,000, with 4.97m streams, making it the fastest-selling track of the year so far.
The single was up against the tropical house cover of Tracy Chapman’s Fast Car by Jonas Blue, which is at No 2, while last week’s No 1 – Stitches by Shawn Mendes – falls to 3.
The rest of the singles chart sees the burgeoning return of Craig David, who has been lifted four places to No 10 with When the Bassline Drops - his first top 10 in eight years. Drake’s new single Summer Sixteen makes its debut at 23, while Sia’s Chandelier returns to the top 40 at 35, with former Liberty X singer Kevin Simm’s rendition on last week’s episode of The Voice giving it a boost.
While Sia made her return on the singles charts, her recent album was held off the top spot this week by David Bowie. Following his death in January, the late musician has become the first act in six years to knock themselves off the top of the official albums chart. His Best of Bowie compilation, originally released in 2002, has replaced his final studio album Blackstar at No 1. He joins Michael Jackson in this feat.
Behind Bowie’s Blackstar, Sia rounds off the top 3. Just 1,213 sales separate Sia’s album This is Acting from the chart-topping Best of Bowie. At present, he occupies seven entries in the top 40.
Elsewhere on the album charts, Adele’s 25 has slipped two places to No 4, while Justin Bieber’s Purpose is at No 5.
This article was written by Harriet Gibsone, for theguardian.com on Friday 5th February 2016 18.00 Europe/Londonguardian.co.uk © Guardian News and Media Limited 2010