Cyrus is believed to have slipped into Melbourne from London on New Year's Eve after finishing her world tour on Tuesday.
A fan saw her at Singapore airport and, after a quick happy snap together, Cyrus let slip she was heading to Melbourne, the Herald Sun reports.
Cyrus fans in the Twittersphere went into overdrive after the photo was posted on the social networking site.
The frenzy grew when a Cyrus fan wrote that she had seen the teen queen on the island.
"On New Year's Eve, I saw Miley at the Pyramid Rock Festival, an event that happens on Phillip Island (Victoria, Australia) every year," a festival goer called Ally wrote.
"We saw Miley at the show chilling with Liam and Chris Hemsworth, a lady that looked about 40 and a few other girls and guys that I didn't recognise.
"She was wearing a Billabong top, a bikini top underneath and denim shorts and honestly looked like every other teenage girl that was there."
The relationship between the red-hot young stars would seem to be intensifying with Cyrus no doubt meeting Hemsworth's family, including dad Craig, mum Leonie and eldest brother Luke, while in town.
While Hemsworth's brother Chris headed back to the US yesterday, the Last Song couple are believed to still be in Melbourne.