The most recent of them was a 10th to another Melbourne Cup entrant, Jukebox Jury, in the Prix Kergorlay (3000m) at Deauville in late August.
It has proved a hot form race with the winner and second horse having won group one races since.
Nigge said the stable would have preferred to see a better showing from Americain before he left for Australia.
"But he's improved a lot since he went to Moonee Valley last week."
Nigge said Americain weighed in at 525kg after his work yesterday, which puts him within one good gallop of his Cup-winning weight of last year.
"He is 5kg more than in the Cup," she said. "He will be the same weight on Cup Day."
Last year, Americain won the Geelong Cup, setting himself up for his ground-breaking Melbourne Cup victory.
"I think he's nearly the same and he'll show us Saturday how he is," Nigge said. "After Saturday, we will know a lot of things."
- AAP