Madonna greets Instagram with risqué photos

Madonna officially joined photo-sharing app Instagram on Sunday, and proceeded to share two racy images with fans.

In one picture, the 54-year-old stares seductively into the camera while sipping a martini with a couple of green olives swimming in the cocktail.

"Cheers motherf-ckers!" Madonna, who sports blunt blonde bangs and a lacy black bra, wrote in the caption.

A second photo focuses on the "Like a Virgin" singer`s cleavage after an intense workout. "Addicted ...