Treve defeated in Prix Ganay
Treve suffered her first defeat when outbattled by Cirrus Des Aigles in the Prix Ganay at Longchamp.
The two principals fought out a tremendous finish in the final furlong and though Treve got her head in front, Cirrus Des Aigles got up in the final strides to strike for trainer Corine Barande-Barbe and jockey Christophe Soumillon.
The first two drew clear of Norse King in third.
Frankie Dettori tried to hold Treve up at the rear of the field, but the Prix de l'Arc de Triomphe winner got no cover on the outside and made up a lot of ground quickly in the middle part of the race.
After Belle De Crecy weakened early in the straight, Ed Dunlop's Joshua Tree made a brief bid for glory but he soon faded as Cirrus Des Aigles and the Criquette Head-trained Treve took over.
It looked as though Treve's class would see her though against the eight-year-old Cirrus Des Aigles but, with the benefit of two runs already this year, his fitness proved a decisive factor.
BetVictor cut Cirrus Des Aigles from 9-1 to 4-1 and pushed out Treve from evens to 2-1 for the Prince of Wales's Stakes at Royal Ascot.
Barande-Barbe felt the early pace had suited her charge and is now eyeing a trip to Epsom for the Investec Coronation Cup on June 7.
She said: "I'm very proud of what he did today - he never was better. I thought the strong pace helped us and it was obviously one of his finest moments.
"On reflection, if the there had been a stronger pace in the race against Frankel (2012 Champion Stakes at Ascot), we might have made that a bit more interesting but now all roads will lead to the Coronation Cup."
Soumillon hailed Cirrus Des Aigles, who was conceding 3lb to Treve, as "perfect" and believes the gelding had shown his best form.
He said: "I'm very, very happy. Although it's the first Group One of the season, it's not the biggest race but then again, the match was built up like a big game and my horse was perfect.
"He had his track, his ground and two races under his belt - it made sure he would operate to the maximum - but this is really something extraordinary for racing.
"It's what we love in European sport - horses so closely matched and fighting it out together. He is probably on his top level of form and to beat Treve, he had to be there."
Head-Maarek felt the ground might have gone against her charge and she remains confident of avenging the defeat should the pair clash again this term.
She said: "Maybe there was too much rain, it was sticky out there and we had too much ground to make up. It was a very good run but the only thing I will say is that my pacemaker (Belle De Crecy) went too fast.
"The winner had had two races already and the fitness was there.
"If she comes out of it well, in principal we will be going to Royal Ascot. We might have lost a battle, but we haven't lost a war.
"She is brave but the other horse is stronger with those two runs this year and he loves that ground. She ran a grat race but he was fitter than we were.
"In the rematch, I'm sure we can get it back. She took the lead but in the end he's come back at us - that's racing. Horses are not unbeatable, that is for certain."
Harry Herbert, racing manager for Sheikh Joaan al Thani's Al Shaqab Racing, insists the Prince Of Wales's Stakes at Royal Ascot in June remains very much on the agenda.
He said: "It's frustrating in that she went to the front and you could see it was going to be a battle. The winner's form was very strong and he was always going to be a big danger.
"The fitness deal with your first run on this ground means so much and on this going she doesn't have that zippity-zip.
"It's all very much to play for in the bigger picture and we will be heading to Royal Ascot as planned."