Sunday's Australian Idol is Acoustic Night, which will see our performers face the daunting challenge of performing without the full band, and instead the stripped-down accompaniment of acoustic guitar, piano and percussion (maybe even a trumpet!). Making it even more thrilling for contestants, they will be able to play their own instruments for the first time this series. Marty and Matt could barely hide their delight when the announcement was made by Andrew and James on last Monday's show.

If that wasn't exciting enough, Australian music legend Ian Moss will mentor the Idols in the lead up to this special night, and has already been working with them in top secret workshop sessions.

Mossy, as he is known to his legions of fans, is part of seminal Aussie rock band Cold Chisel, alongside Jimmy Barnes, who have scored hits with "When The War Is Over" (as performed by Cosima De Vito in the first season of the show) and "Khe San". As a solo artist Ian has had further hits with "Telephone Booth" and the No.1 smash "Tucker's Daughter".

He has just released "Let's All Get Together", his second acoustic album which features pared-down versions of his well-known songs "Flame Trees" and "Out Of The Fire".

"If it was five years ago and somebody said, 'You're going to spend quite a bit of time doing acoustic', I would have said, 'I don't think so'," laughs the man best known for rock. But the success of his acoustic albums makes him the perfect choice to guide the Final Nine through the raw and honest genre.

If that's not enough, on Monday the Final Nine will join Mossy on stage for an acoustic performance of his song "Choir Girls". It is the first time in Australian Idol history that the Verdict Show group performance has included an outside performer, and no doubt it will be one not to miss!