Rihanna has proved why she rules Instagram… by posting a no-makeup selfie.

Following the news that RiRi has inked her brand new Puma deal, the Bajan babe took to the image-sharing website to show off her natural beauty.

[related]In the pic, RiRi bites her lip as she looks seductively at the camera and while it’s not 100% obvious, it seems the star may have taken the pic in the bath - her preferred location for shots of this sort.

And, Rihanna wasn't the only one posting pics of herself, with Justin Bieber also taking to Instagram to share a snap of the Diamonds singer in her underwear.

He accompanied the sexy photo with the caption: "Happy Holidays", but later deleted the pic an hour or so later.

But, thanks to eagle-eyed fans, here's a screen grab for your viewing pleasure…

Happy Holidays indeed!