Demi Lovato and Christina Aguilera. Picture: Bang Showbiz

Demi Lovato and Christina Aguilera have confirmed they are duetting on their new song 'Fall In Line' at the 2018 Billboard Music Awards.

The 'Tell Me You Love Me' singer and 'Beautiful' hitmaker have confirmed they are to give their new single 'Fall In Line' - which features on Christina's new LP 'Liberation' - its live debut at the annual ceremony on May 20 at Las Vegas' MGM Grand Garden Arena.

READ: Demi Lovato wants fans to see she's not perfect

The pop stars both shared pictures of one another on their social media accounts announcing the performance.

Christina wrote: "May 20th @BBMAs. @ddlovato. #FallInLine (sic)"

May 20th. @BBMAs. @ddlovato. #FallInLine.

A post shared by Christina Aguilera (@xtina) on

And Demi added: "May 20th @BBMAs. @xtina. #FallInLine (sic)"

May 20th. @bbmas. @xtina. #FallInLine

A post shared by Demi Lovato (@ddlovato) on

The powerhouses have been teasing fans about the song for weeks, and it was finally unveiled when Christina announced the full track-listing for her first record since 2012's 'Lotus' last week, which also includes new track 'Accelerate' with Ty Dolla $ign and 2 Chainz.

It follows Janet Jackson being announced as the recipient of this year's Icon Award.

The 'Nasty' hitmaker will also sing at the bash for what will be her first televised performance in nine years.

Janet will join the likes of Neil Diamond, Stevie Wonder, Price, Jennifer Lopez, Celine Dion, and Cher as previous recipients of the honour.

From 1990 to 2001, the 'Rhythm Nation' hitmaker earned 18 Billboard Music Award nominations, having won 10 of them.

Janet's performance and Demi and Christina will be joined by previously announced acts Camila Cabello, Ariana Grande, Dua Lipa, Shawn Mendes, and Korean pop group BTS at the ceremony. 

Kelly Clarkson will be hosting the event, which will be broadcast live at 8pm EST, and 5pm PST on May 20.