Nicole Kidman, Keith Urban perform duet

The Sun claims that the couple sang together at the G'Day USA Ball, which honours Australian celebrities.

The pair reportedly covered the Men At Work track 'Down Under' when Kidman presented actor Simon Baker with an award.

However, Kidman insisted that the performance would not be repeated.

"This was a one-off as a duo," she said. "We're not going to be the new Jackie Trent and Tony Hatch."

Urban has previously said that he would consider recording duets with Kidman.

/Digital Spy/