Taylor Swift and former One Direction member Zayn Malik have redeemed 2016 for their fans, releasing a surprise new song together for the soundtrack to Fifty Shades Darker.

I Don’t Wanna Live Forever unexpectedly appeared in the US iTunes Store just before midnight Friday US eastern time. iTunes described it as “two of pop’s brightest stars [teaming up] for a passionate duet”.

The song, the first to be released from the soundtrack for the upcoming Fifty Shades Darker film, is a suitably smokey mid-tempo number that sees Malik and Swift swapping verses.

Malik takes the chorus in trademark falsetto: “I don’t want to live forever, ‘cause I don’t want to be living in pain/I don’t want to fit wherever, I just want to keep calling your name/’Til you come back home.”

Swift shared news of the single with her 82.2 million Twitter followers, with only the obtuse comment: “Z | T | 50”.

It had been retweeted nearly 15,000 times in an hour.

While Malik was similarly restrained in his post, the pair’s fanbase was anything but.

“Zayn and Taylor” and #idontwanttoliveforever were trending on Twitter as the two stars’ combined following of over 100 million fans reacted to the unforeseen collaboration with liberal application of caps lock.



ZAYN AND TAYLOR HAVE A SOMG WTKSKSKWJDJJD IDK HOW TO FEEL ABOUT THSI — 🤘🏼 (@Snapback_zarry) December 9, 2016

ZAYN AND TAYLOR DID A SONG TOGETHER FOR FIFTY SHADES DARKER. AND NONE OF THAT SENTENCE MAKES SENSE. — j (@carefreeharold) December 9, 2016

ZAYN AND TAYLOR COLLAB I REPEAT ZAYN AND TAYLOR COLLAB — Suzy (@SuzzyZayn) December 9, 2016

Some connected the collaboration with Malik’s girlfriend, model Gigi Hadid – a high-profile member of Swift’s “squad”.

I blame Gigi Hadid for Zayn and Taylor's collab — busé (@knewbetterbuse) December 9, 2016

The song was #1 on the US iTunes chart within an hour of its release. “Well that escalated quickly,” commented Swift on Instagram.

Malik posted a Polaroid of the pair posing with one of Swift’s cats.

Jack Antonoff, who collaborated with Swift on some tracks on her record-breaking 1989, tweeted that the song “came together very quickly”.

He wrote I Don’t Wanna Live Forever with Swift and Sam Dew, a hip-hop songwriter best known for the hook to the 2013 track by Wale, LoveHate Thing.

Antonoff recorded Swift and produced the track at his home. Malik sent his contribution from Los Angeles.

“We did it in a week basically. I’ve never had something come out that quick,” Antonoff said.

i don't wanna live forever came together very quickly. wrote it with taylor and sam dew and produced it at home mostly on paper sounds — jackantonoff (@jackantonoff) December 9, 2016

recorded taylor at my house. zayn sent parts from LA - we did it in a week basically. i've never had something come out that quick — jackantonoff (@jackantonoff) December 9, 2016

I Don’t Wanna Live Forever is available to buy from the US iTunes store for US$1.29. It is not known when it will be available in other territories.

It is the first new music Swift has released in 2016, though the star featured prominently in headlines due to her high-profile breakup with Calvin Harris and short-lived relationship with Tom Hiddleston.

Despite an absence of new music, she was the highest-paid musician in 2016, earning $60m more than One Direction – the boy band Malik left last year.

In March, Malik released his debut album, Mind of Mine, to positive reviews, and published his autobiography at the age of 23.

Fifty Shades Darker will be released early next year.