Stanley Tucci Says Naomi Ackie's 'Moving' Performance in Whitney Houston Biopic Gave Him 'Chills' (Exclusive)

'I Wanna Dance With Somebody' is in theaters Dec. 23.

It's not easy to step into the shoes of a musical icon, but Naomi Ackie does just that in I Wanna Dance With Somebody, the upcoming Whitney Houston biopic.

The film -- the first-ever telling of Houston's story to be officially sanctioned by her family -- stars Ackie as the talented diva throughout her rise to fame, most legendary moments and untimely death.

"The most challenging part of portraying Whitney Houston is portraying Whitney Houston," the actress said with a laugh in ET's exclusive look behind the scenes of the upcoming biopic. "It's very hard to play a superstar."

It's even harder when that superstar is someone you grew up idolizing. 

"I remember the first time I saw her," Ackie recalled. "She produced Cinderella with Brandy, and she played the Fairy Godmother.... I was obsessed with that film!"

Ackie spent six months in vocal training working on Houston's accent and singing style -- and even donned prosthetic teeth for the role. In the film, the actress sings along with Houston's vocals on some of her biggest hits.

"The only person who can sing like Whitney Houston was Whitney Houston, let's face it," said Stanley Tucci, who plays record exec Clive Davis in the film. "But [Naomi] has a beautiful voice herself, so she's singing these songs along with the playback and it gives you chills....She's incredibly moving."

The real-life Davis is also a producer on the film, and said he hopes the biopic gives fans an even closer look at who the diva really was.

"The purpose of this film is to show the full Whitney, but it is also to show the great talent," he shared.

Ackie had to agree. "I hope people will walk out first off with all of her songs in their head," she shared, "but also, [feeling] like, 'I didn't know that,' and, 'Wow, what must [that] have felt like.'"

I Wanna Dance With Somebody is in theaters Dec. 23.