Keith Urban and Nicole Kidman celebrated their eighth anniversary Wednesday in Melbourne, Australia.

And Keith happened to have a concert that night. So he did indeed give Nicole a super-sweet shout-out in the middle of the show. And yes, Nicole was there.

In fact, Keith told the crowd a story about Nicole having cold feet a month or two before the wedding.

So Keith did what he does best -- he wrote her a song.

It was called "Once in a Lifetime." And apparently it helped calm Nicole's insecurities because, well, they're married, aren't they?

Keith played that song Wednesday night and dedicated it to Nicole.

He said, "Eight years, baby girl, this is for you tonight my love; I love you so much.