The Hughie Morrison-trained Marmelo displaced last year's winner Almandin at the top of the market on Sunday and has been well supported since, firming to $7.50 on Tuesday.
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.
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On Cup eve in the country's biggest betting race, Marmelo was the TAB's favourite, displacing last year's winner Almandin who is out to $9 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.
