The four-year-old was comprehensively beaten in Group race company earlier in the season but two Listed wins prompted Fabre to step the Shamardal filly back up in class.
Baltic Baroness duly rose to the occasion in winning by a short head from Pomology and Fabre admitted he thought she would have secured such a success earlier than now.
“I’d always hoped she would win a big race, but I must admit I thought it would have happened before now,” said Fabre.
“She is going to be a force to be reckoned with next year.
“She has just taken time to mature. She is from a very backward family, but now she is going the right way.
“We built her confidence up at a lower level which helped.
“She won’t go for the Arc unless her owner insists as she would have to be supplemented.
“That might be it for this year, but there is a possibility she may go to the Breeders’ Cup.”
Fabre’s Prix de Paris winner Gallante, who is owned by Coolmore, could finish only sixth in the Prix Niel on much quicker ground than he appreciates.
“Gallante looked very one-paced in the Niel, he needs soft ground to be at his best,” said Fabre.