Michael Buble is about to take the stage in the New York Christmas special where he gave some insight on the night that will be filled with holiday cheer.

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On Tuesday, TV Line posted the details on Buble's performance that will air on Wednesday night, featuring Ariana Grande and Mariah Carey. According to Buble, Grande is "the real deal" and when he called her to ask her on the show, he "loved her within the first five seconds."

Buble then mentioned Carey's appearance even though it sounded like he had more to say about Grande.

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"Mariah was great, but you know. Mariah is Mariah," the classy jazz singer told reporters before the taping. "She's this beautiful wonderful diva. What can I tell you? Ariana Grande just showed up three minutes early, she knew the whole song perfectly."

Grande and Buble duet the song "Santa Claus is Comin' to Town." She is also supposed to sing a solo rendition of "Last Christmas."

"She couldn't be any kinder and more professional," Buble added about his "Problem" co-star. "If I was a fan before, you can times it by a million now."

Buble also revealed that being a part of this show is something he takes deep pride in even though it's a challenge.

"It's a great joy for me," he said. "It's fulfilling for me. But I'd be lying if I didn't say that it's probably the most challenging thing that I do each year."

Michael Buble's Christmas In New York airs on Wednesday, December 17 at 8 p.m. ET on NBC.

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