Even though Keith Urban and Miranda Lambert's 'We Were Us' debuted on the Aussie singer's recent album 'Fuse,' it actually has been years in the making.

Urban tells ABC News Radio that the seed for duet was planted in 2005 when the talented Lambert opened for him on tour. “We used to do a song every night during my set,” he says. “I always loved singing with her, and I thought our voices went really well together.”

Their voices went so well together that the planted seed or inkling of an idea sprouted into a full-blown necessity. It became clear to Urban that they needed to do a duet, but it needed to fit their voices perfectly -- any old duet would just not do. He never gave up on looking for a song that would fit the bill, and when he heard 'We Were Us,' he knew it was the one.

“I just called her up and sent her the song, and she loved it. Her and Blake [Shelton] actually came to the studio and hung out for a few hours… We sang it together and it was done,” the crooner recalls.  

Although Urban may not have anticipated the duet taking almost 10 years to find, it was definitely worth the wait. The two superstars delivered their riveting song at the 2013 CMA Awards, and everything from their onstage chemistry to the emotive lyrics came together for a memorable pairing.

Hopefully this will be the first of many collaboration between Lambert and Urban, as the sassy songstress joked backstage at the CMA Awards that he owes her a guest appearance on her next CD, since 'We Were Us' appears on 'Fuse.' We, and probably every other country fan, think that's a brilliant idea.