Video: Mariah Carey's disastrous lip-syncing failure

Mariah Carey had a pretty awful day at work at the Jazz and Blues festival in Jamaica Saturday night - when she forgot the words to her own song.

Unfortunately, as she stumbled with her vocal, her lip-sync track kept playing 'Fantasy' with gusto, as Mariah tried her best to mouth along with the words, seeming flustered and unable to catch the right part of the song.

The Jamaica Observer reports that 'Fantasy' was the very first song of the set (which contained four costume changes) and "it was apparent that Carey was relying heavily on a backing."

Fans posting online give different versions of events, with some claiming she lip-synced the entire set, while others insist it was just one or two songs.

"Her voice was somewhat off and she, even at one point, utilised a throat lozenge to help improve her output," the Observer said.

"As the set progressed, her vocal quality improved but her audience, for the most part, was detached from the performance, as she seemed unable to draw them into the performance despite a string of hits."

In December, Maria was widely criticised for a poor performance at New York's Rockefeller centre, when she sang her festive hit 'All I Want For Christmas Is You' at the tree-lighting ceremony.

Footage leaked at the time showed her unable to sing the high notes in rehearsal, and there were reports she had insisted on delaying the pre-recording for unknown reasons.

Carey's personal life has also come under close media scrutiny recently, after her split with husband Nick Cannon last year. She confirmed a Las Vegas residency in January - where she will headline the Caesar's Palace Coliseum show.

Speaking at the time about performing some of her older songs - like 1995's 'Fantasy ', Carey said: "I've never done this before. Some of these songs I'm like, 'Really, I'm gonna do this again, OK?'"