Keith Urban "freaked out" when he heard Meryl Streep would be joining the cast of 'Big Little Lies'.

Keith Urban

Keith Urban

The 50-year-old country music star has admitted he was thrilled to find out that the legendary actress would be starring alongside his wife Nicole Kidman in the second season of the HBO drama, as he thinks Meryl's performance will be "riveting".

He said: "Yeah, of course [I freaked out]. It's an amazing thing. It's a win-win all around. I think it's going to be riveting."

And the 'Blue Ain't Your Colour' hitmaker - who has daughters Sunday, nine, and Faith, seven, with his spouse - admitted he would even consider collaborating with Meryl on a duet for the show's soundtrack.

When asked about recording a song with Meryl, Keith said: "Of course I would! [Nicole] would drive it. It would be a collaborative thing."

The musician couldn't help but gush over Nicole's performance in the show either, as he says he's "proud" of his 50-year-old spouse.

He added to 'Entertainment Tonight': "It's been awesome. I'm so happy and proud of Nic. And the success of 'Big Little Lies' has been extraordinary."

Last week, it was revealed that 68-year-old Meryl would be joining the second season of the show as Mary Louise Wright, who is the mother of the abusive Perry Wright, played by Alexander Skarsgard.

Perry - who is the husband of Nicole's character Celeste - was revealed to have died in the first season of the show, and Meryl's character is said to be "concerned for the well-being of her grandchildren" following his passing.

HBO previously said of the show's second season: "[It will explore the] malignancy of lies, the durability of friendships, the fragility of marriage and, of course, the vicious ferocity of sound parenting. Relationships will fray, loyalties will erode ... the potential for emotional and bodily injury shall loom."