Michelle Payne swapped her riding silks for a flowing silk dress as she helped launch the Melbourne Cup carnival, carrying the Cup she famously won in 2015.

Gliding into Flemington in a flowing red dress while mounted on a white horse with the Melbourne Cup in hand was a little more glamorous than when Michelle Payne first held the coveted trophy aloft.

Payne was back on course on Monday to launch the Cup carnival and swapped her silks for a silk dress, since her role will be that of commentator rather than jockey.

She became a household name in 2015 when she steered 100-1 chance Prince of Penzance to victory, becoming the only female jockey to have won the iconic race in its long history.

She said those three minutes changed her life.

"It's amazing to think that one race can change your life as much as the Melbourne Cup has changed mine," said Payne, whose story was told in the 2019 film Ride Like A Girl.

"It's incredible to think what one three-minute race has done for my life, and the movie and the opportunities I've been able to take from that is mind-blowing."

The 38-year-old will retire from riding early next year but will continue training, devoting her attention to stayers in particular, and targeting the Cup. She said the time was right.

"It's been something that I've obviously been thinking about and had on my mind for the past sort of eight years since winning the Melbourne Cup, but just wanted to wait till the right time," she said.

"I've got some really nice horses at home that I want to ride into the autumn but this carnival does feel different because it's sort of an end of an era for me."

Payne said she knew she had a special horse in "Prince" and that everything in his Cup preparation had gone their way

"You need to have the right horse but you need to have the perfect preparation as well," she said.

"They've got to be peaking at the right time. It was amazing with him because in the lead-up in the week before, everything just seemed to be falling into place.

"He was flying and his final gallop on the Friday before running in the Cup was the best he'd ever worked in his life and thankfully it all worked out for me."

She said her pick for the race this year was French-bred, Irish-trained gelding Vauban, who is the short-price favourite at $4.00.

Vauban is trained by shrewd veteran Willie Mullins, who also prepared Max Dynamite when Payne beat him into second in 2015.

"I like Vauban," Payne said.

"I was really blown away by his effort when I saw him at Royal Ascot and Willie Mullins has obviously come very close.

"He finished second with Max Dynamite the year Prince won it.

"I'm sure he's definitely keen to take the Cup home and he looks like he's got the right horse so he's my pick, but obviously, as always in the Cup, it's very open."