Reports suggest the young star suffered a meltdown backstage and refused to go on, leaving her backing singer, Nadia Aya, to take the stage at Flemington Racecourse.

Insiders claim a wardrobe malfunction forced Mauboy to pull out of the appearance at the last minute.

On Wednesday (04Nov15), the singer took to social media and assured fans she was OK, writing, "Thank you to everyone for all the messages of concern, I am OK.

"I am so sorry I didn't perform at the Melbourne Cup yesterday, I was really looking forward to it and of all the days for things to go wrong, unfortunately this was the one. I am so sorry to everyone for the disappointment."