Australian Olympic swimming legend Ariarne Titmus has been unveiled as the first slider for Big Freeze 11 at the MCG, revealing the emotional moment she was asked by Neale Daniher to take the plunge.

The latest edition of the FightMND will be a special occasion after Daniher was named Australian of the Year in January.

And it was at that ceremony that Titmus first learned she was in the family’s sights to head down the slide at the King’s Birthday AFL clash next month.

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“This is an unbelievable honour,” she told Channel 7 on Thursday night.

“It’s not about me being a slider, it’s about the cause we’re sliding down the slide for.”

Titmus was quite literally tapped on the shoulder by Daniher’s daughter and FightMND leader Bec.

“I actually met Neil at the Australian of the Year (ceremony) and we were just in a line-up to get head shots,” she said.

“Basically Bec tapped on my shoulder and he asked me to be a slider.

“I got so emotional and started crying because it was just a really big moment for him becoming Australian of the Year, and being asked — it’s been amazing working with them.”

Titmus has been a familiar face around the AFL supporting her beloved Hawthorn since taking a break from the swimming pool after the Paris Olympics.

The Big Freeze secret has been difficult to keep.

“Six months almost,” the four-time gold medallist laughed.

“But it’s important to keep the secret because the cause we are fighting for is so important and what the Danihers have done for MND is incredible.”

Titmus revealed this year’s Big Freeze theme as ‘iconic Australians’ in honour of Daniher’s status as Australian of the Year.

She would qualify to go down as herself, of course, but already has an idea in mind.

“Hopefully the costume I’m wearing is going to keep me nice and warm,” she said.

“I’m not telling. No hints!”

Ahead of Big Freeze 11, Neale Daniher will sit down with Hamish McLachlan for a special edition of Unfiltered next Wednesday night.