They were riding high for five weeks, but now it's the ultimate comedown for Lukas Graham, as Mike Posner overtakes them in a nail-biting chart battle to score this week's Number 1.

7 Years has been leading the way all week, but I Took A Pill In Ibiza made a last-minute overnight rush to the top spot, beating Lukas Graham to Number 1 by a mere 261 combined chart sales – the closest chart race of the year so far.

It's the narrowest margin between the Top 2 since summer 2007, when Timbaland and Keri Hilson's The Way I Are beat Kate Nash's Foundations to Number 1 by a mere 16 copies, knocking Rihanna's Umbrella off the summit in the process.

Lukas Graham may have fallen to Number 2, but 7 Years is still the most streamed track of the week, notching up over 4 million listens. Zara Larsson's Lush Life reaches a new chart peak today, climbing one spot to Number 3, while Fifth Harmony's Work From Home powers seven spots to Number 4

Rounding off the Top 5 this week is Work from Rihanna, who kicked off her Anti World Tour in Florida last weekend. Highest new entry this week goes to Ariana Grande's Dangerous, new at Number 17. The star showed off her knack for celebrity impressions – and her powerful lungs – when she guest-presented US comedy show Saturday Night Live at the weekend. 

Good news for Selena Gomez: Hands To Myself zooms 11 places to 21, while her mate Joe Jonas and his band DNCE rocket 16 places – Cake By The Ocean breaks into the Top 40 for the first time at Number 26. Zayn scores his second solo Top 40 hit since leaving One Direction, with Like I Would going straight in at Number 30.

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Watch Posner's video for 'I Took A Pill In Ibiza' here: