Not everything went to plan for connections of Vadamos in the lead-up to the Cox Plate.

And not everything went right for the French horse in the race either.

The only international runner in this year's Cox Plate opened up a five-length lead mid-race on Saturday but that was erased by the 600m mark as Winx started to make her winning run.

A Group One winner in France at his most recent start, Vadamos battled on in the straight to finish fourth on Saturday but was almost 10 lengths behind Winx.

"He was just too keen," Vadamos' jockey Mark Zahra said.

"I just couldn't get him to switch off. The whole way I just thought he was going a bit too hard. I thought he did a good job to run fourth considering."

Zahra picked up the ride on the Andre Fabre-trained horse on the eve of the Cox Plate after two other jockeys had already been ruled out.

Damien Oliver was initially booked to ride Vadamos but he missed Saturday's meeting because of a suspension so connections called on champion Hong Kong-based rider Joao Moreira.

But Morieria was forced to relinquish the ride on Thursday because of an approaching typhoon in Hong Kong.

Hong Kong Jockey Club officials ruled Moreira couldn't travel to Melbourne amid fears he wouldn't be able to return in time for Sunday's Sha Tin meeting.

Vadamos was aiming to become the second internationally trained horse to win the Cox Plate after Aidan O'Brien's Adelaide won in 2014.