Tres Blue may be the Gai Waterhouse-trained Melbourne Cup runner that has got under everyone's guard.

His French breeder, Andreas Rapp, said the intention was to run Tres Blue in the prestigious Prix de l'Arc de Triomphe but after being contacted by Australia's Round Table Racing, things changed.

"We chatted about the Melbourne Cup and the idea of bringing him here. That's how it developed," said Rapp, who has come to see the phenomenon known as the Melbourne Cup for himself.

"We know the race. There have been French winners the last couple of years and it's very popular in France."

Although he was keen to sell the horse to the syndicate he also retained 35 per cent.

Jockey Tommy Berry says Tres Blue, a $21 chance, has natural speed and will be up on the pace.

In his past five races, competing in Germany and France, the four-year-old has won three times, and run second and third in the others.

"He hasn't raced over 3200 metres yet but he feels like he will stay all day," Berry said.

Last year, Berry rode in his first Melbourne Cup on Glencadam Gold who finished sixth and will be calling on that experience on Tuesday when he jumps out of gate 20 at Flemington.

"It's a very high-pressure race and you have to save everything for the last 200 metres. It's a long way down the straight," he said.

"I believe I am on the right horse to do it, so it makes it a lot easier."

Berry says his biggest threat in the race comes from the other Waterhouse-trained horse and Cup favourite Fiorente, who he has been riding in trackwork.

"I've been riding Fiorente in work and he has come through the Cox Plate better than what I would have hoped for someone who has to ride against him," Berry said.

Berry has been on a fish diet to get down to the 51kg Tres Blue will carry but he says it now feels like his natural weight.