UPDATE: Lady Gaga's 'Bad Romance' won in Round 2! Vote for ‘Bad Romance’ in Round 3 of the competition here.

Welcome to March Music Madness! Here at PopCrush, we've selected 32 of the most iconic pop songs released from the '80s to today (divided into brackets by decade) — and now it's your job to vote and decide which song will be named the Greatest Pop Song of the Modern Era. May the best song win!

It's time for Round 2 in our challenge to find the Greatest Pop Song of the Modern Era! In our previous face-offs, Kelly Clarkson beat Taylor Swift by more than 13%Lady Gaga conquered Christina Aguilera with an even wider margin: 35%! Now it's the 'American Idol' champ against Mother Monster. Who has the greater pop song?

Kelly Clarkson's 'Since U Been Gone' is both a power anthem and a chart-topper! The song proved that Kelly has a career far beyond her 'Idol' win, and even earned her a Grammy in 2006. But is it enough to take on one of the century's biggest superstars?

Lady Gaga has quite a few hits on her resume, but none took the radio by storm quite like 'Bad Romance.' The chant-heavy track scored Gaga two Grammys. Did we mention it was certified 10-times platinum?

Which song should be named the Greatest Pop Song of the Modern Era? You can vote for Kelly or Gaga once an hour until the polls close at 12 PM ET on March 18. The competition is getting fierce, so vote, vote, vote! The winning song in this battle will move on to Round 3.