The pair have long been friends, initially rising to fame as the warring witches Elphaba and Glinda in Broadway musical Wicked.

But they will enjoy a new kind of rivalry on 23 September (16) when Idina drops her album Idina. and Kristin releases her record, The Art of Elegance.

Idina announced the news of her album on Facebook Live on Thursday (04Aug16), telling fans she opted to use her moniker as the record name because "I want you to know me on a first-name basis, I guess."

She added the offering is "really personal", explaining: "I poured my heart out and used my music as a place to kind of figure some things out. It’s a really personal album."

Idina hit headlines back in 2014 when she was introduced by John Travolta at the Oscars as "Adele Dazeem". And she referenced the hilarious mistake as she explained why she had opted for punctuation at the end of the album title.

"There’s a little period after it that kind of gives a little attitude, but that’s just ‘cause of those, like, four guys that bullied me in middle school that always screwed up my name. And then maybe one older guy a little more recently,” she smiled.

The album will be Idina's first since her holiday themed record Holiday Wishes in 2014.

Kristin, meanwhile, teased the release of The Art of Elegance on Twitter on Thursday (04Aug16), sharing a snap of a calendar with a red kiss mark on the 23 September box.

Idina and Kristin formed a close bond when they starred in Wicked back in 2002 and 2003. Kristin was nominated for a 2004 Tony Award as Best Leading Actress in a Musical for her performance, but lost out to her co-star. While their lives have moved on significantly since then, the Glee star said in a recent interview that they will always share a history due to their time in the hit musical.

She told Playbill: "One of the things that happened with Wicked is that we both knew we were in something special, and only she and I know what that was. We were in it together, you know? There isn't a day that goes by when I'm not thankful for that show, and I know she feels the same."