Post Malone has said he is “beyond honoured” to have collaborated with Taylor Swift on her new album The Tortured Poets Department.

The US rapper and singer features on Swift’s lead track “Fortnight”, which became Spotify’s most-streamed song in a single day upon its release.

Post Malone, real name Austin Richard Post, also stars in the music video for the track alongside Swift and Dead Poets Society stars Ethan Hawke and Josh Charles.

“It’s once in a lifetime that someone like [Swift] comes into this world,” Post Malone said. “I am floored by your heart and your mind, and I am beyond honored to have been asked to help you with your journey I love you so much. Thank you Tay.”

Announcing the music video and single, Swift said she had been “a huge fan of Post because of the writer he is, his musical experimentation and those melodies he creates that just stick in your head forever”.

“I got to witness that magic come to life firsthand when we worked together on ‘Fortnight’,” she said.

According to Spotify, The Tortured Poets Department achieved more than 300 million streams in a single day after it was released.

Among the most prominent songs is track five, “So Long, London”.

Swift is known for placing her most heartbreaking or personal song in the fifth spot of each album’s tracklist; “So Long, London” is widely believed to address her split from her boyfriend of six years, British actor Joe Alwyn.

Other songs allude to her brief fling with The 1975 frontman Matty Healy, whom Swift takes aim at on “Fortnight” and “The Smallest Man Who Ever Lived”.

Taylor Swift and Post Malone in the ‘Fortnight’ music video (YouTube/Universal Music Group)
She also seems to chastise her own fans and team on “But Daddy I Love Him”, which shows her defiant in the face of naysayers telling her she shouldn’t be with “the one I want”.

The track, which takes its title from the Disney animated film The Little Mermaid, appears to reference the furore that erupted when Swift was reported to be dating Healy.

“I’d rather burn my whole life down/ Than listen to one more second of all this bitchin’ and moanin’/ I’ll tell you something ‘bout my good name/ It’s mine along with all the disgrace/ I don’t cater to all these vipers dressed in empath’s clothing,” she sings.

The Independent’s critic Helen Brown awarded Swift’s album five stars, writing that it is “a terrific reminder of her storytelling powers”.