Beauty Parlour justified favouritism in winning the Poule D'essai Des Pouliches (French 1000 Guineas) at Longchamp on Sunday.
Elie Lellouche's charge was stretching her unbeaten record to four but this victory was far from routine, Christophe Soumillon taking her to the front a furlong out.
She had to be driven out to the line as Aidan O'Brien's Up came through to challenge but was always holding her rival.
Topeka was third, narrowly ahead of another Ballydoyle filly, the fast-finishing After.
Lellouche said: "It was good that Christophe went when he did, as she had a difficult race. She is a great filly and we shall go for the Prix de Diane (French Oaks).
"She has an entry in the Coronation Stakes, but I prefer to keep her at home. I think there is still more to come from her. Certainly the way the race went today didn't suit her at all and she did well to win."
Soumillon said: "She is a great filly and I'm proud to win such a big race with her. I was forced to gallop on the outside, even though the ground was better on the inside.
"I went a bit earlier than I thought I would, but I needed to make that move there and then."
O'Brien said of Up and After: "I'm delighted with the way they ran. Up was coming home well, she had a bad draw and ran a great race. She stayed on well. The other filly ran well, too."
Asked where Up might go, he said: "I'm not sure, but she can do a lot of things. She can step up in trip."
Mick Channon said of Samitar who finished ninth: "I'm a bit disappointed but nothing's gone right for her and we shall see what happens. There is always another day."