UPDATE: 'N SYNC's 'Bye Bye Bye' won in Round 2! Vote for ‘Bye Bye Bye’ 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!

We're one step closer to determining the Greatest Pop Song of the Modern Era! In Round 1, 'N Sync beat Justin Bieber by 37 percent (!!!), while Rihanna just barely held Beyonce at bay. Now, in Round 2 of the competition, the boy band will face off against the provocateur. Which is the greater pop song: 'Bye Bye Bye' or 'Umbrella'?

'N Sync may have said "bye bye bye" to a bad relationship, but they said "hello" to a massively successful song! 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. The track is considered one of the band's greatest and has stood the test of time.

Rihanna established herself as a successful performer with 'Umbrella.' Her 2007 hit scored her a Grammy and made "ella ella ay ay" a pop culture fixture. The track kicked off Rihanna's edgy image and helped establish her as a risk-taking artist.

Which pop song is greater? You can vote for 'Bye Bye Bye' or 'Umbrella' once an hour until the polls close at 12 PM ET on March 18. Make sure to vote often so your favorite track makes it through to the next round!