Happy Birthday, Justin Bieber AND Ke$ha! Today Biebs turns 19 while Pop's Dirty Girl welcomes 26. The two artists' careers have gone head-to-head in recent years—both have No. 1 albums, chart-topping singles and massive world tours. So to determine who really owns March 1, Fuse is pitting each artist's songs, albums, videos and collaborations against each other, and collecting readers' votes, in order to crown a champion. It's March madness—click "next" and vote now!