Selena Gomez is so lucky to have a BFF like Taylor Swift, for the obvious reasons, but mostly because she's quite the seasoned dater who knows the best way to get back at an ex -- through music. And at a private, acoustic concert for UNICEF on Saturday, Selena did just that.

Although Selena has stayed pretty mum on her break up from Justin Bieber so far, she definitely alluded to the fact that her  life is in a new place during the intimate performance. In fact, she covered her pal's song "I Knew You Were Trouble", which is reportedly about Taylor's own latest ex Harry Styles. Check it out!

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In addition, Selena also played another well-known break up song when she covered Justin Timberlake's "Cry Me a River," which the Biebs also sang at one of his own concerts after their first break up a few months ago.

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"I've been through a lot the past few months," Selena revealed, before breaking into the song. "It's been weird and sad and cool. This song definitely speaks to me."

Which cover of Selena's did you like better?