Aidan O'Brien has raised doubts about the participation of Love in the Prix de l'Arc de Triomphe, amid the prospect of significantly testing conditions in Paris on Sunday.
The Galileo filly has carried all before her this season, claiming the 1000 Guineas at Newmarket before adding the Oaks at Epsom and Yorkshire Oaks at York.
She has been aimed at the Arc since her victory on the Knavesmire in August — and with it an eagerly-anticipated showdown with the John Gosden-trained Enable, who is looking to make history as the first horse to win the Arc three times.
But with the going reported to be very soft and an unsettled forecast before the weekend, O'Brien told the: "When you start getting into extremes — especially when you start talking about heavy ground in France - we have to be realistic.
"We have to make a decision at 9.30am on Friday. Nothing is on or off until we believe things are right."