Sea La Rosa was an impressive winner of the Group One Qatar Prix de Royallieu at ParisLongchamp.
The William Haggas-trained filly was partnered by Tom Marquand for the one-mile-six-furlong event, run on very soft ground after persistent rain.
Travelling strongly in a field of 10, the chestnut pulled away to cross the line a length ahead of Jannah Flower.
Francis Henri-Graffard's Verry Elleegant, winner of 11 Group One contests in Australia including the Melbourne Cup, was unplaced after rerouting to the race after it became evident she would not make the cut for Sunday's maximum field in the Prix de l'Arc de Triomphe.
Marquand said of Sea La Rosa: "She's been incredible this year to be honest, and the backend of last year. She just seems to be getting better with each run.
"She's got the heart and the talent to see it through and to get a Group One on the board for Mrs (Ling) Tsui (of owner Sunderland Holdings) is amazing because she's been a huge supporter and a great presence here. I'm very privileged to be a small part of it.
"I wouldn't have a clue what the plans are. To be honest it doesn't look like she's done yet, but I'll leave the big decisions to the boss (Haggas) and Mrs Tsui – they don't usually get it wrong!"
Sea La Rosa is a daughter of the Tsui family's 2009 Arc hero Sea The Stars, who was himself a son of Urban Sea, the mare who won the 1993 Arc for the family and produced some legends of the turf, including the great sire Galileo.
Christopher Tsui said: "This meeting has been good to us and today was the same.
"It was very emotional watching her win and my heart was racing.
"She's a beautiful filly, and talking to (trainer) Jean Lesbordes he commented how she reminded him of Urban Sea.
"There are no plans for her we will let the dust settle and see."
Maureen Haggas, trainer's wife and assistant added: "She is great. She is very tough, a really tough filly, she really is. She has improved and improved and is hard as nails and has improved all year.
"She is brilliant. It is great for the yard."
Mark Zahra made the trip from Australia to partner Verry Elleegant in seventh, but he felt the race did not work out in her favour.
He said: "I suffered to be in a spot where I couldn't move and was effectively stuffed.
"She tried all the way but it was hard to get a line on the leaders."
David Menuisier's Ottilien was the third-placed horse, beaten a length and a quarter in a run that delighted her trainer and could tee her up for an outing at Ascot or another overseas run in Germany.
"When she won the Prix Turenne in Saint-Cloud, she needed the race, but she proved today that she's up to this class. I am very happy," he said.
"We decided to slow the pace during the race, because despite the fact that nobody wanted to go to the front, we didn't want to set the race up for the rest of the field.
"She doesn't have a turn of foot but the filly does stay on, and we got beaten by two fillies who have a good turn of foot. I think she will stay in training at four. As she has had a light campaign, it's possible that she will run again this year.
"The first option is Ascot and the second would be to supplement her for the Grosser Preis von Bayern, which is run in Munich. I think that she would be hard to beat in Germany over 2,400 metres (12 furlongs) and given heavy ground."
