Gwen Stefani has revealed Sia offered her 'Elastic Heart'.

The No Doubt star told Taylor Swift on 'The Voice' on Tuesday (29.10.19), when she appeared as a 'Mega Mentor', that the Australian pop star and songwriter had offered her the track before she made it a hit in 2013 with rapper The Weeknd and producer Diplo.

Speaking after contestant Kyndal Inskeep revealed her song choice, Gwen told the 'Shake It Off' hitmaker: ''This is so weird, because Sia sent me this song for me to do.''

Both Gwen and Taylor were impressed by the talent show hopeful's rendition.

Taylor said: That was so interesting -- and not in the way that people say that passive-aggressively.

''I loved that you stripped it down ... your tone is so beautiful.''

Gwen chose to take Kyndal through to the next stage of the competition.

She said: ''She sings from her heart and she just has so much style to her voice.

''Those are the kind of singers I'm looking for.''

When Sia released the track, Gwen hadn't put out a solo record since 2006's 'The Sweet Escape', but her band No Doubt pleased 'Push and Shove' the year before in 2012.

The 50-year-old pop star - who is dating her fellow 'The Voice' coach Blake Shelton - previously revealed she completely lost her ''confidence'' after releasing 'Push and Shove'.

She explained: ''I think after doing 'Push and Shove' and having it not be successful, I lost a lot of confidence. Songwriting, for me, has always been traumatic, and I've always made all these excuses. But I've realised that you have to just accept that it was a gift: ''I don't know where it came from, I don't know how I did it, but I did write all those songs, and I gotta do it again.''