is a makeup maven!

The singer posted a sexy snap of herself on Twitter on Friday, posing topless in the latest ad for MAC Cosmetics' Viva Glam campaign. 

RiRi, who's sporting a platinum blonde 'do, covers her breasts with her hands in the high-fashion snapshot.  

"Here’s my new AD Campaign with @MACcosmetics for #VIVAGLAM !!! Coming soon to MACcosmetics.com #staytuned," the brunette beauty wrote, along with the new photo.

MAC Cosmetics is thrilled with the collaboration, posting the same pic with the caption, "Introducing Rihanna's new shade of MAC VIVA GLAM! Available lipstick and Lipgloss this January. @badgalriri #VIVAGLAM."

We think the songstress is a perfect fit for MAC, but what do you think of her first campaign ad? Tell toofab in the comment section below, and click "Launch Gallery" above to see more Rihanna's sexiest TwitPics!

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