Unbeaten dual Classic winner La Cressonniere will not run in Sunday's Prix de lArc de Triomphe after trainer Jean-Claude Rouget revealed the filly had suffered a setback.
Second favourite in the ante-post market behind Postponed, the unbeaten 3yo had been hoping to add to her victories in the French 1000 Guineas and Oaks with success in Sunday's showpiece.
Rouget told Press Association Sport: "There is a problem, not a very strong problem but we had to do treatment and that means we cannot run her on Sunday.
"It's not very important for the future, but enough for her not to run on Sunday.
"We don't know exactly what it is. She has to go to the topography and so on to have it checked it out. The problem is towards the back."
Also ruled out is one-time Derby favourite Midterm. The son of Galileo missed the Epsom showcase after suffering a stress fracture and his owner's racing manager Teddy Grimthorpe told the Racing Post: "New Bay will run in the Arc, but not Midterm.
"Midterm is fine and worked nicely on Saturday. We are considering some options at the moment. Having come back from injury we have to give him every chance to get on track really well."
Derby winner Harzand will have a workout on Tuesday to determine whether he will take his place on Sunday.
Trainer Dermot Weld confirmed the 3yo was recovering well from the cut he sustained when unplaced in the Irish Champion Stakes at Leopardstown earlier this month.
Weld said: "Harzand is well and will do a bit of work on Tuesday. Hopefully they get some rain in Paris. He'll do some work on Tuesday morning and we'll see how he is."
"Providing we're happy with him on Tuesday, I'd say he'd be all set."
Also confirmed is last year's third New Bay. Trained by Andre Fabre, the 4yo was last seen finishing fourth in the Irish Champion Stakes.
Grimthorpe said. "He ran really well in Ireland, we were delighted with him," "He's come back from there in really good form and worked nicely since so we couldn't be more pleased. Vincent Cheminaud will ride."