Singer-songwriter Taylor Swift treated fans in attendance at yesterday's Formula One grand prix in Austin, Texas to a live performance of "This Is What You Came For", which she co-wrote with ex-boyfriend Calvin Harris.

It was confirmed back in July that she was the writer credited under the pseudonym Nils Sjöberg, and Scottish DJ Harris, who was her boyfriend for over one year, told his followers on Twitter that she did a great job penning the lyrics for the smash-hit single:

"And she sings on a little bit of it too. Amazing lyric writer and she smashed it as usual. I wrote the music, produced the song, arranged it and cut the vocals though. And initially she wanted it kept secret, hence the pseudonym."

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Watch Swift performing the song below: