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Keith Urban admits he had no idea his music would be powerful enough to land him four Grammy nominations.

"I wrote and recorded Defying Gravity to touch upon the power of the human spirit," the country singer, 42, tells "I had no idea that it would've connected in the way that it did."

The Australian-born star -- who is currently traveling alongside wife Nicole Kidman in London for her upcoming Nine movie premiere -- tells Us the experience has been unbelievable.

We saw it night after night on the Escape Together Tour and to now end the year with these nominations is pure magic," he says.

Urban -- who has won two Grammys for his songs "You'll Think of Me" and "Stupid Boy" -- is nominated for best male country vocal performance, best long form music video, best country collaboration and best country album.

Defying Gravity -- the singer's sixth studio album -- is up against albums by the Zac Brown Band, George Strait, Lee Ann Womack and Taylor Swift, who landed eight Grammy nominations when they were announced Wednesday.