$10,000 bet on fairytale horse that could cost a bookie $500,000

British hopes of plundering a first Melbourne Cup continue to grow with Marmelo poised to start a commanding favourite as the race's fairytale horse Single Gaze stands to be a horror result for bookmakers after an erratic Call of the Card.

Nervous bookmakers turned away a flood of money intended to back the popular Marmelo during Monday's event, which included a single bet of $10,000 on Single Gaze at $51, which threatens to rip more than $500,000 from CrownBet's coffers.

Stubborn bagmen wouldn't budge from an $8.50 quote about Marmelo on the eve of Australia's biggest betting race as punters shied away from Lloyd Williams' Almandin making it back-to-back wins.

Marmelo's fast-finishing sixth in the Caulfield Cup has seen him elevated to the top of betting markets with most bookmakers - and they are convinced he will start even shorter.

William Hill boss Tom Waterhouse was among the Call of the Card audience frustrated in not being able to get set on Marmelo. He had a bet to win $100,000 blocked.

Punters' dream shot: Melbourne Cup outsider Single Gaze attracted big bets at the Call of the Card. Photo: AAP

Punters' dream shot: Melbourne Cup outsider Single Gaze attracted big bets at the Call of the Card. Photo: AAP

But a frenzy of smaller bets flowed for Hugh Bowman's mount, which is destined to be Britain's best hope of snapping their Melbourne Cup curse.

"I've marked him $6 and I think he'll run close to that," CrownBet's Matt Tripp said.

"You go back a couple of years and Fame Game's run in the Caulfield Cup was almost identical. It ran $5.50, I think this is a weaker race and I just can't see why it won't run much shorter than the $8 or $8.50 quote.

"I just thought in his Caulfield Cup run he was on the wrong leg the whole way and every time he balanced up and got a bit of momentum he improved in the run. He kept wanting to spit the bit out and I don't think Caulfield suited him.

"A big track at Flemington drawn to possie up seventh or eighth as the race tempo builds he's going to be right in the finish."

Tripp did his best to inspire a subdued Crown auditorium, holding the initial call on more than half of the Cup field.

It is believed he held close to twice the sum of the other three bookmakers fielding at the function, Robbie Waterhouse, Mark Sampieri and Warren Woodcock.

Tom Waterhouse backed Wall Of Fire ($14-$13) to win $200,000 with the Melbourne Storm part-owner Tripp and also stands to win $100,000 if Big Duke or Libran are successful.

The 2015 runner-up Max Dynamite ($16 to $15), one of three runners in the race for Irish training genius Willie Mullins, was one of the most popular runners at the Call of the Card alongside Humidor ($11 to $10) and Johannes Vermeer ($11).

One punter had a bet to win $1 million on Cox Plate runner-up Humidor with Woodcock shaved back to a potential collect of $250,000, while Waterhouse's father Rob stands to lose a quarter of a million if Single Gaze ($51 to $41), trained by Canberra's Nick Olive, can win.

He initially refused the punter to win $1 million on the mare, agreeing to part with $250,000 if Single Gaze helps Kathy O'Hara be the second female jockey to win the race in the last three years.

"I hope it gets beaten," Rob Waterhouse said. "I didn't like it. I make lots of mistakes, but I marked it 100s. I thought Wall Of Fire has got a great chance. On form Humidor looks to have a really good chance in the race, I just don't think it will be suited by the 3200 [metres]."

Tom Waterhouse was adamant Marmelo and Wall Of Fire, both of who include Melbourne entrepreneur Aziz Kheir in the ownership, were the leading chances.

"You saw here all the tough money wanted to be on [Marmelo] and the bookies didn't want to lay it," he said. "I think the bookies were keen to lay Almandin and I like Gai's horse [Cismontane] down the bottom as a roughie.

"I think it's a great Cup to bet in and I think we have to lay them all and let the punters work it out."

Sportsbet bucked the Marmelo ($8) trend until late on Monday night, finally posting him favourite over defending champion Almandin ($9).

"We've taken so much money on Marmelo that we simply had to make him the new favourite," Sportsbet's Christian Jantzen said.

"More than twice as much money has been placed on Marmelo compared to Almandin, who's the second most popular in the eyes of the punters.

"We're scared stiff of Almandin, which will be a terrible result for us. We think he's still the horse to beat despite the last start disappointment and the rise in weight from last year.

"Punters are also latching on to the Single Gaze fairytale which is fine by us and we're happy to lay her."

This story $10,000 bet on fairytale horse that could cost a bookie $500,000 first appeared on The Sydney Morning Herald.