Mariah Carey Alleged Isolated Vocals Track Surfaces High Note Struggle

12/4/2014 6:12 AM PST

Mariah Carey -- Isolated Vocal Track Surfaces ... High Note Struggle (VIDEO)

A video appearing to be the isolated vocals from Mariah Carey's NBC performance Wednesday night has found its way online ... and she struggled.

The video was posted on a site called The Concourse and it seems authentic. It matches the version that aired on TV with full accompaniment.

Mariah seems fine during the meat and potatoes portion of "All I Want for Christmas is You"  ... but she has difficulty when she exercises her upper octave range.  

It's interesting for sure.