It has been decided: Adam Liaw and Callum Hann will be up against each other for the much-coveted title of the 2010 MasterChef Australia on Sunday night.

Claire Winton Burn has failed the ultimate catering challenge on Thursday night, where she, Liaw and Hann were asked to make a dinner for Australia's Governor-General Quentin Bryce and 30 of her guests.

The three finalists must take control of one course each as they made a dinner for the guests at the Government House in Canberra.

Liaw took charge of an entree of two trout tartlet, while Winton Burn prepared the main of a roast rack of lamb and Hann dished up a chocolate fondant with orange jelly and hone anglais for the afters.

"I was the worst cook on the day and you just have to take it on the chin," Winton Burn said.

"In that place at that time there was probably nothing else I could have done.

"It was devastating to hear that I was out; I've given nine months of my life and given up everything to be here.

"But I'm really proud of making it as far as I did."

Winton Burn said she had opted for the most difficult dish and no one is to be blamed but herself. She was happy though that Hann had made it through ahead of her.

"We both want it and yet we both want it for each other," she told judges.

According to judges Matt Preston and George Calombaris, Winton Burn failed the challenge because her lamb was served more than 15 minutes late.

They also said that the size of the lamb cutlets were not more uniform and were a little overdone.

"It breaks my heart to say it but you've not made the cut," Preston said.

"Today it came down to the kitchen and you just needed that help that Callum didn't need."

The finale show on Sunday is anticipated to break records when it goes on air, especially with audience figures of over 2.5 million on its final week.

Last year's finale was watched by a record-breaking 3.725 million viewers.