Famous for his association with triple Cox Plate winner Winx, Hugh Bowman gets his best chance yet to also become known as a Melbourne Cup winner.

The heavyweight rider has had few genuine chances over the years in the world's richest handicap but punters believe English horse Marmelo can change that on Tuesday.

Before his eye-catching sixth in the Caulfield Cup, the Hughie Morrison-trained Marmelo won the Prix Kergorlay (3000m) at Deauville.

Two winners of that testing staying race, Americain (2010) and Protectionist (2014), have gone on to win the Melbourne Cup over 3200m.

On Cup eve in the country's biggest betting race, Marmelo was the TAB's $8 favourite, displacing last year's winner Almandin who is out to $9.50 and one of six horses running for his owner Lloyd Williams who has won the race a record five times.

The Darren Weir-trained Humidor, who chased Winx home in the Cox Plate, is at $10 alongside Johannes Vermeer, third in the Caulfield Cup for Irish trainer Aidan O'Brien and co-owner Williams.

But the worst result for the TAB is Single Gaze, the Caulfield Cup runner-up.

The diminutive mare from Canberra is at $41 but well supported by her loyal following.

She is trained by Nick Olive, who believes people continue to underestimate her toughness, and will be ridden by Kathy O'Hara, the only woman with a ride in the Cup famously won by Michelle Payne two years ago.

"It would mean the world to me, not only just me and my career but also to win for Nick and all of the owners in this horse," O'Hara said.

"She's come from many humble beginnings and she's just come so far in her career. For her to come back after a really nasty fall, it just says volumes about her temperament, her will to win and her toughness."

After Single Gaze, the TAB's next worst result is Marmelo followed by $101 chance Gallante, German horse Red Cardinal ($19) and Hartnell ($26), trained by James Cummings for Godolphin.

Gallante is another horse running for Williams while Red Cardinal is prepared by Protectionist's trainer Andreas Wohler.

The scratching of Who Shot Thebarman on Sunday has reduced the field to 23 and reignited the call for emergencies to be named for the Cup.

Victoria Racing Club chairman Amanda Elliott, who has a share in the Chris Waller-trained Libran ($41), says she is in continuing discussions with the TAB to resolve the issue by next year.