Taylor Swift may surprise her longtime fans with her latest career move. The country-turned-pop star has recorded a sultry duet with former One Direction singer Zayn Malik for the upcoming film Fifty Shades Darker, the sequel to Fifty Shades of Gray.

Swift built her career on a sunny, non-sexualized image, and while she's taken a turn in a more mature direction since she left country for pop, she's still quite demure compared to many of the top female pop stars. She joins Malik for a very sultry, R&B-influenced duet on "I Don't Wanna Live Forever," and its inclusion in the upcoming film -- based on the best-selling book series that centers around sexual domination and bondage -- is sure to raise some eyebrows. They recorded in secretly and dropped it by surprise Thursday night.

The superstar shared the sound clip above from the song via Instagram late Thursday night (Dec. 8), along with a shot of the cover of the single.

Just hours later she shared that the song was No. 1 on iTunes, commenting, "Well that escalated quickly."

Swift and Malik perform the song in the film's trailer, which features more of the same graphic, highly sexualized content that made the first film in the series so controversial. It's a big change of pace for the singer, who has managed to maintain an air of innocence in her image even as she has expanded her songwriting to explore some harder-hitting, more adult themes.

Swift wrote "I Don't Wanna Live Forever" with fun. guitarist Jack Antonoff, along with Sam Dew. Antanoff described the process in a tweet Thursday night, saying the song came together "very quickly" and that he "produced it at home mostly on paper sounds."

Fifty Shades Darker is set for release on Feb. 10 of 2017.

Swift also made headlines on Friday (Dec. 9), when she announced she was partnering with the ACM to donate $200,000 to the Tennessee wildfire relief efforts.

How Well Do You Know Taylor Swift?

Nastiest Lawsuits in Country Music

More From Kalamazoo's Country