Keith Urban is quickly climbing up the charts with his latest single, 'We Were Us,' a duet with Miranda Lambert. But while the song marks the first time the two country superstars have recorded a track together, the Aussie says he has hoped for the past several years that they would have a chance to collaborate at some point.

Urban invited Lambert to join him on his 2005 Alive in '05 Tour, and as is his custom, he invited the opening act to perform with him during his set.

"I always loved the way our voices sounded together," he explains (quote via CMT). "So probably in the back of my mind, I've always hoped that I could find something we could do."

The 45-year-old says he knew as soon as he heard the song that Lambert would be the perfect choice.

“‘We Were Us’ came along and it’s not the kind of song Miranda would normally do, but her voice is the first one I heard in my head,” he tells Radio.com. “I called her up and sent her the song and she loved it and came to the studio ... I’m just so happy at the way it turned out.”

'We Were Us' can be found on Urban's latest album, 'Fuse.' He will continue his Light the Fuse Tour this weekend with shows in Oklahoma and Louisiana. See his complete concert schedule here.