Britney and Gaga moved on, LMFAO fell hard (twice), and Katy Perry won some and lost some: Round 1 of Billboard.com's Hot 100 March Madness is over, with 16 No. 1 Hot 100 singles moving on to the second round from the field of 32. With the first round of head-to-head match-ups completed, it's time for some more voting!
To help determine the winner of Hot 100 March Madness, check out the updated bracket of songs, and vote for your favorites in the head-to-head match-ups below.
