High Jinx benefited from a brilliantly judged front-running ride by Ryan Moore to land the Prix du Cadran at Longchamp.
James Fanshawe's stayer was given plenty of rope from an early stage in the two-and-a-half-mile contest and Moore made the opposition pay.
The 5-1 chance still held a handy advantage rounding the home turn and although both home runner Bathyron and Dermot Weld's Irish challenger Pale Mimosa tried to make inroads, High Jinx had enough in reserve to hold them at bay.
Bathyron was a clear second ahead of Pale Mimosa in third, while Andrew Balding's Whiplash Willie finished fourth and may well have been closer but for meeting interference early in the straight.
Fanshawe said: "Ryan was determined to set his own pace out in front and gamble as to whether he would stay doing it like that, which was not what I had in mind, but I'm really pleased that Ryan got it right.
"This horse has been placed in the same race twice before, always just missing out, but he's much less ground dependent now that he has been gelded.
"I've had a fantastic year in France - for a second I thought I was going to win the Opera with Ribbons. I just wish my horses in England were running as fast as they are over here."
Weld said of Pale Mimosa: "She has run a good race but the ground has dried out for her a bit. We'll get her home now, see how she comes out of the race and make a decision."