Is Lykke Li really Mary-Kate Olsen? It took us a minute...

Lykke Li sang her heart out on "The Carson Daly Show" this week.

OK, we'll admit it.

When we first tuned in, a minute into her song, we were captivated and mesmerized.

Our first thought, "Wow! Mary-Kate Olsen is really good! Who knew?"

Anyway, love this strange and haunting Swedish singer.

Check out her MySpace page.

And keep reading to watch her second performance that night.