Video: The 10 Most Popular 'Glee' Performances

 

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4. Defying Gravity

Downloads: 375,000

Lea Michele is a Broadway-trained singer at heart, but we didn't get to hear the full extent of her musical theater chops until the first season's ninth episode, where Rachel and Kurt Hummel (Chris Colfer) battled it out for the chance to sing this "Wicked" ballad at sectionals. Rachel won out after Chris sadly botched the song's final high note, but the two paired up offscreen to record the official single, making for a powerful duet that fans loved.

  next: "Teenage Dream"