Clive Cox revealed Heartache returned home with a pulled muscle after suffering her first defeat in the Prix Robert Papin at Maisons-Laffitte on Sunday.
The Kyllachy filly was a hot favourite to remain unbeaten in the Group Two contest following her stunning display in the Queen Mary Stakes at Royal Ascot last month, but had to make do with minor honours in third behind Karl Burke's Unfortunately and Tom Dascombe's runner-up Frozen Angel.
Heartache was far from disgraced, beaten just half a length, but Cox feels she is better than she showed on the day.
"Sadly she's just not 100 per cent. I think she's pulled a muscle over her back," the trainer told At The Races.
"Gerald (Mosse) was quite right in his summing up after the race. It was the first time he's ridden the filly, but he felt we might find something in the next 24 hours and he was right.
"Our physio has been on the case already and she's happy that we've got a handle on it. I hope she can reproduce a more Ascot-like performance next time.
"That said, fair play to the two colts that beat us. I thought they were two nice colts."
