Moonlight Cloud could clash with top colt Intello next weekend after mowing down Lethal Force inside the final furlong to win the Prix Maurice de Gheest at Deauville for the third successive year.
Clive Cox's grey lost nothing in defeat, conceding 3lb to the Freddie Head-trained five-year-old, but he simply had no answer to Moonlight Cloud's finishing burst in a blistering time.
Adam Kirby attempted to make most on Lethal Force, tactics which had worked so well in the Diamond Jubilee and July Cup, but he had to work quite hard to get over to the rail.
Once there Kirby tried to wind it up in front but Thierry Jarnet always looked confident, and once he asked Moonlight Cloud to go and win the race the response was immediate and the five-year-old was able to come home alone.
Gordon Lord Byron made late headway to finish third while Gale Force Ten showed up well for a long way before fading close home.
Head intends to send Moonlight Cloud back to Deauville for the Prix Jacques le Marois as long as she bounces out of the race well.
"She's a very special filly and that was one of her best performances," said Head.
"There were four Group One winners, it was a tough race but she broke the course record.
"She gave her everything, she's not a horse you can hit much, she gives her all without the whip so that is maybe why it looked like she won easier than maybe she did.
"The plan remains the same, to run in the Marois next week, but as she has given everything I'll just see how she is over the next two or three days.
"A race against Intello (French Derby winner) would be great."
Cox was proud of his stable star but the general feeling was that the grey was not quite at the peak of his powers.
He said: "He's lost nothing in defeat, he's run very well and I'm very pleased with him.
"It was run in a course record time and the ground was only just good so he's run a very brave race.
"At the end he was just beaten by a very good filly who was winning the race for the third time.
"Adam just felt he wasn't quite as good as he was at Newmarket. We were happy to come, don't get me wrong. We're very pleased with him but obviously we'd have preferred to have won.
"We'll just see how he comes out of this before making any plans, we'll get him home and take it from there.
"The winner is a special filly."
Elsewhere on the card, Jane Cecil's First Mohican had to settle for a close third in the Osaf Prix de Reux at Deauville won by Tres Blue.
Winner of four of his five lifetime starts this Group Three over a mile and a half looked a nice opportunity for Henry Ponsonby's injury-plagued five-year-old.
Tom Queally set out to make all but was challenged on the run for home, with Montclair forcing up his inside and Henri Alex-Pantall's Tres Blue on his outer.
Tres Blue, who had finished second in the German Derby on his most recent outing, prevailed by three-quarters of a length.