Hot 100 March Madness Finals: Vote Now!
Hot 100 March Madness Finals: Vote Now!

Britney and Katy powered on, Adele squeaked by P!nk, and Lady Gaga lost in a major upset: Round 2 of Billboard.com's Hot 100 March Madness was even more exciting than the first round, with 8 No. 1 Hot 100 singles moving on to the third round from the field of 32. With the second round of head-to-head match-ups completed, it's time for some more voting!

To help determine the winner of Hot 100 March Madness, check out the updated bracket of songs, and vote for your favorites in the head-to-head match-ups below.

The original bracket was comprised of the 32 most recent songs to top the Hot 100 chart. The match-ups within the bracket were determined by the dates in which each song topped the Hot 100: the most recent No. 1, fun.'s "We Are Young," is matched up against the 32nd most recent No. 1, Rihanna's "Rude Boy," and so on. Click here to see the original bracket.

On Friday (Mar. 23), we'll reveal the 4 songs that won their third-round match-ups, and another round of voting begins. On Friday, Mar. 30, a Hot 100 March Madness champion -- the No. 1 single that you think is the best smash hit of the past two years -- will be crowned.

Looking back at the second round of voting, a number of unbelievably tight races yielded some surprising results -- none more shocking than B.o.B and Bruno Mars teaming up to defeat Lady Gaga's "Born This Way." "Nothin' On You" earned 51% of fan votes over 49% for "Born This Way," and made its way into the Elite 8 over Gaga's most recent No. 1 hit. Bobby Ray versus Gaga wasn't even the closest race in the second round: Adele's "Set Fire To The Rain" overtook P!nk's "Raise Your Glass" by less than 300 votes, and it was enough to push the U.K. sensation into the third round. Rihanna's "Only Girl (In The World)" versus Katy Perry's "Calfornia Gurls" proved to be another photo finish, but Rih Rih's "Loud" single eked out 52% of the votes, and the win.

Meanwhile, Britney Spears' "Hold It Against Me" defeated Rihanna's "Rude Boy" with a decisive 61% of the fan votes, while Bruno Mars breezed by Far*East Movement, with "Just The Way You Are" earning 56% of the votes compared to 44% for "Like a G6." Now, the two juggernauts face off against each other in the third round.

On the other side of the bracket, Katy Perry became the only artist to have two solo songs in the Elite 8 (Rihanna and Bruno Mars also appear on two songs), as "Teenage Dream" earned 55% of the fan votes against Ke$ha's "We R Who We R" and "Firework" exploded past Usher's "OMG" with 60% of votes. And the Eminem-Rihanna combo proved superior to the Rihanna- Drake duo, with "Love The Way You Lie" taking home 61% of the votes in its contest against "What's My Name?".

Vote now for your favorite tracks below, and be sure to discuss the bracket in the comments section!

Questions? Comments? Let us know: @billboard

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