Ryan Reynolds was only casually promoting his new movie, "Free Guy," on TikTok when the one and only Mariah Carey joined the actor for a hilarious "Fantasy" collaboration. 

In the TikTok published by Reynolds last weekend, he was seen sitting in front of his phone, lip-syncing to the 1995 hit single. He even left a caption that read, "Go see Free Guy this weekend so I can stop doing this."

And as it reached the chorus, he continued lip-syncing to the song and formed a butterfly motion with his hands.

The video that the actor posted, which reached 21 million views and still counting, caught the attention of Carey on Tuesday as she made her own hilarious side-by-side 'duet' video.

The singer also left a comment replying to Reynold's video which said, "That wasn't part of the plan! ️"

   @mariahcarey ##duet with @vancityreynolds That wasn’t part of the plan! ️ ##FreeGuy ##Fantasy  ♬ Fantasy - Mariah Carey     

Reynolds The Best Film Promoter

According to Daily Mail, Mariah Carey's "Fantasy" was featured during a sequence on the comedy film where Reynolds' character "Guy" comes across Jodie Comer's character "Millie." Reynolds even shared the clip from the movie on Twitter last week, confirming that Comer was also there singing their song rendition.

"The Proposal" actor never even hid his excitement as he admitted in an interview with Variety that he is a huge Mariah Carey fan.

He also stated that the 1995 song by Carey is the "engine of the movie," in which case it became the song used on the TikTok video. "I am a huge Mariah Carey fan. It really was one of those weird things that happened naturally," Reynolds said.

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Ryan Reynolds In Touch With 'Fantasy' Singer

In the interview, Reynolds also mentioned, "I write to music anyway, and I initially put a song in the script by The Outfield called "Your Love."

"It's an old '80s tune. It's great, but it just didn't have that epic scale I was looking for," the actor proceeded and told the source how he discovered "Fantasy" on his playlist, and "everything clicked in.

Unfortunately, Reynolds said he did get in touch with the singer on using the song for the movie, which was released in theaters on August 13. "She's just been awesome about it," Reynolds admitted.

"Fantasy" was Carey's lead single for her 1995 album "Daydream," which became her ninth single that made it to the Billboard Hot 100 charts.

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