UPDATE: 'N Sync's 'Bye Bye Bye' won in Round 1! Vote for 'Bye Bye Bye' in Round 2 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 a battle of huge hits from teen heartthrobs! Justin Bieber made millions of girls swoon when he swagged into the pop music scene with 'Baby.' However, earlier that decade, 'N Sync took over radio waves with 'Bye Bye Bye.' Which song do you think should be named the Greatest Pop Song of the Modern Era?

Although Justin was a young teen when 'Baby' was recorded in 2009, his confidence and sweet vocals helped skyrocket him to fame. It didn't hurt that the chant-like chorus of 'Baby' was completely infectious. Justin has since adapted a more R&B tone to his music, but we'll always remember dancing to his breakout hit, which charted on the Top 10.

'N Sync coined dance moves and pop culture jargon with 2000's 'Bye Bye Bye,' the lead single from their sophomore album. The rhythmic breakup track, which was nominated for a Grammy, helped to define the direction of pop music at the beginning of the decade. The success of 'Bye Bye Bye' also helped 'N Sync to earn the top first-week album sales for 'No Strings Attached' -- a record they still hold today.

Which track is more worthy of the Greatest Pop Song of the Modern Era title? Vote for Justin or 'N Sync once an hour until the polls close on March 11 at 12PM ET. The winning song will move on to the next round!