Lemaire faces a protracted spell on the sidelines after sustaining a fractured collarbone in an Arab race at Saint-Cloud.
Agent Helen Barbe confirmed: "He's had a very light schedule for the past 10 days, but you can never choose when you're going to have an accident.
"It's only a collarbone and he'll be back soon enough.
"Christophe is fine within himself, but is probably more disappointed for the clients who he was meant to be riding for this weekend."
A decision has yet to be made on Lemaire's deputy for Stacelita, who controversially defended her unbeaten record in last month's Prix Vermeille.
The Jean-Claude Rouget-trained filly finished second to Dar Re Mi, but the winner was demoted into fifth after being found guilty ocausing interference with another rival.
Michel Zerolo, racing manager for Stacelita's owners, said: "Jean Claude-Rouget has no sense of urgency at this stage and will explore all possible options.
"He needs to discuss the situation with her owners and a decision will be made by the end of the day."
