UPDATE: Rihanna's 'Umbrella' won in Round 1! Vote for 'Umbrella' 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!

Beyonce and Rihanna have mastered the art of creating catchy, iconic pop songs. Bey launched a fashion trend, a signature dance move and thousands of copycats with her hit 'Single Ladies (Put a Ring on It.)' Rihanna, on the other hand, started a debate on the meaning of 'Umbrella' in one of her biggest songs to date. Which song should be known as the Greatest Pop Song of the Modern Era?

Beyonce's anthemic 'Single Ladies,' her Grammy-winning song that hit No. 1 when it was released in 2008, serves to empower all of the ladies out there who don't have a ring on it. Between the song's catchy hook and the understated black-and-white video, there's no denying that Bey created a movement. She had everyone from Joe Jonas to Justin Timberlake parodying the song, which is still popular today.

Rihanna adapted her edgy image with the launch of 'Umbrella' in 2007. The track's infectious "ella, ella" chant helped send RiRi to superstar status. 'Umbrella' also won a Grammy and sat at No. 1 on the charts, and its dramatic video suited Rihanna's flair for the avant-garde while providing the launching pad for the rest of her Top 40 career.

Which song is more iconic? You can vote for Beyonce's tune or Rihanna's track once an hour until the polls close at 12PM ET on March 11. Remember, the winning song will move on to the next round and may be named the Greatest Pop Song of the Modern Era!