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Viral Video: Pentatonix Cover Lorde's Hit "Royals"
The biggest hit of the week already has a hit cover.

Lorde's "Royals" reached No.1 on Billboard Hot 100 on Wednesday, dethroning some singer named Miley Cyrus.

Pentatonix -- the band that won Season 3 of the NBC competition "The Sing-off" -- just released a cover of the hit. But instead of instruments, Pentatonix performs it a cappella. And in a gender reversal, Mitch Grassi sings the lead vocals. It's pretty much been on repeat all day here at toofab. Check it out:

Of course, Lorde's version ain't too shabby either.

The 16-year-old New Zealander appeared on VH1's "Big Morning Buzz Live with Carrie Keagan," where she sang "Royals" live (take that, Britney Spears). Find out how Lorde celebrated hitting No. 1 and listen to her performance:

Which version do you prefer?