March Madness 2017 is a month-long competition on PopCrush to determine the best of the best of South Korean boy bands and girl groups.

This round is now over! Vote for Sistar in the semi-finals here!

The battle begins today between S.E.S. and SISTAR — one veteran act and one of today's hottest troupes — now going head-to-head in the first round of PopCrush's 2017 March Madness series.

S.E.S. are considered one of first truly massive girl groups upon their debut in 1997. Much to their fans' delight, the legendary group returned 15 years after their last studio album in January of this year called Remember, and are holding a fan meet-up in March.

After debuting in 2011, the girls of SISTAR have made waves in South Korea and abroad, including a hilarious cameo on Family Guy. Following a collaboration with the iconic Giorgio Moroder, the girls are now preparing for a comeback in the first half of 2017 according to reports.

The battle starts now: place your vote between BLACKPINK and Apink. This round ends on March 10.

Join the conversation on social media! Use #PCMarchMadness to discuss this year's competition.

K-Pop Groups That Disbanded Over the Years: