Fifth Harmony is kicking off 2015 with a collaborative cover effort.

Fifth Harmony Collaborating With Jacob Whitesides On 'Uptown Funk' Cover & Fans React On Twitter

The girl group teased fans on New Year's Eve about what 2015 would bring for them.

Ally Brooke Hernandez, Normani Kordei Hamilton, Lauren Jauregui, Camila Cabello and Dinah Jane Hansen publicized fans should mark their calendars for Jan. 7 for the group's first surprise of 2015.

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On Jan. 1, Jauregui took to Twitter to share lyrics to Mark Ronson's song Uptown Funk featuring Bruno Mars.

Her tweet included a link to an Instagram post she made of her and her bandmates singing a snippet of the lyrics she tweeted. Within the short video clip, the text, "#5HIN2015" and "COMING JANUARY 7TH 2015" appears.

Then on Jan. 2, Cabello tweeted, teasing another snippet of the girls singing a segment of the song, but another voice was also present in the short clip.

She asked, "hear any familiar voices?"

Then, singer Jacob Whitesides tweeted the 5H member asking, "who is that???," which led to the 5H Twitter account retweeting him and therefore confirming he's the mystery voice in the Uptown Funk cover that'll be releasing on Jan. 7.

On Saturday, it was Hansen's turn to tease a snippet of the sure-to-be fabulous cover. The vocals are fiercely strong as heard in the clip Hansen shared on her Instagram!

Sunday Hamilton teased another clip, which included some fire emojis in her tweet. The clip she shared featured the lyrics; "I'm too hot," which is fitting for the fire emojis.

Monday was Hernandez's turn to tease the fans.

Whitesides also got in on the teasing with the following clip that really shines a light on his vocal talents.

Their Uptown Funk cover is releasing tomorrow!