It's officially March, which means it's time once again for our annual March Madness — a month-long competition between the most devoted, die-hard fans of our pop favorites to crown the most dedicated base.

But this isn't going to be an easy battle. In fact, we're kicking off with a killer match-up that ought to be a fight to the finish: Britney Spears and her fiercely devoted Britney Army versus Rihanna's ever-loyal Navy.

Both superstars have had incredible years so far, which ought to only rally the stans even more: Britney's had a total resurgence with her newly remixed Piece Of Me residency in Las Vegas as she continues to work on her upcoming ninth studio album — and post tons of hot as ice Instagram videos in the process. Rihanna, on the other hand, finally dropped her long awaited, lane-changing record ANTI, got to "Work" with Drake and just recently performed at the BRITs — and she's got a world tour on the way.

Brit Brit Army? Rih Navy? The time is now: Place your vote below. This round will end at 11:59 ET on March 9.