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 top 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 up 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 hit since leaving One Direction, with Like I Would going straight in at Number 30.

Chart Run: 3-2-1-1-1-2-1-1-1-2-2-5-6-7-5-8-7-11

Adele has kept the seat of the Official Albums Chart throne warm… for herself. 25 is Number 1 for a second straight week, its 11th in total.

The When We Were Young star will surely be on cloud 9 (or would that be cloud 11?) as her album 25 outsold its nearest rival by over 10,000 copies. It’s a feat all the more impressive when you consider 25 is not available to stream, meaning she’s defeating her rivals left, right and centre on physical and digital sales alone.

Adele’s closest competition, Justin Bieber, climbs one place to Number 2 with Purpose, returning to the peak position it debuted at back in November. Despite being the first artist to hold 1, 2 and 3 at the same time on the Official Singles Chart with tracks from the album, Purpose has still yet to become Justin’s second Number 1 album.

The rest of the Top 5 features last week’s usual suspects, but in a different order. Jess Glynne’s I Cry When I Laugh falls one place (3), and David Bowie’s Best of Bowie and Coldplay’s A Head Full of Dreams both hold firm, at 4 and 5 respectively.

There are a total of seven new entries this week on the chart. Incarnate, the seventh studio album from Killswitch Engage gives the metalcore group their first UK Top 10 album, besting 2013′s Disarm the Descent which peaked at 15.

Painkillers, from The Gaslight Anthem’s Brian Fallon, is the next newbie at Number 13, and Canadian singer-songwriter Alessia Cara also makes a solo debut, with Know-It-All entering at 14.