EXCLUSIVE: Keith Urban Dishes on Plans for Nicole Kidman's 50th Birthday

The 49-year-old singer also opened up about a possible collaboration with his wife.

Keith Urban has something in the works for Nicole Kidman's birthday.

ET's Cameron Mathison caught up with the singer at the GRAMMYs in Los Angeles on Sunday, and though his wife was across the pond at the BAFTAs, he knew better than to reveal his big plans for Kidman's special day.

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"I'm planning stuff right now that I can't talk about!" he confessed. "I feel incredibly lucky and blessed, definitely."

Kidman will turn 50 in June, and Urban just a few months later, making 2017 "a big year all around." So big, in fact, that Urban can't even reveal his Valentine's Day surprises.

"I gotta keep it a secret!" he said.

Whatever Urban has planned, Kidman is definitely in for a treat. The country singer sweetly shared the inspiration for his duet with Carrie Underwood, "The Fighter" (which they performed at the GRAMMYs), revealing that he tries to protect Kidman "every day."

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"It's a song about protecting the one you love, so that they don't have to take the blows of the world, and can stay pure," he dished.

"I always think that when people go, 'Oh, I'm very thick-skinned,' I always feel like saying, 'I'm so sorry.' It's not really a great attribute to be thick-skinned, it's kind of nice when someone can take the blows for the one you love. That's what the song's about," he continued. "I try [to do that for my wife] every day."

As for whether Kidman will be his next duet partner, the country star says to stay tuned.

"We're so spontaneous, everything is just always in the moment," he said. "So we'll see what happens!"

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