A decision will be made this morning on whether Saffron Walden makes a dramatic late switch from Saturday's Epsom Derby to Sunday's French Derby at Chantilly. Heavy rain in the south of England has hit an Epsom track which had already been described as having a "good to soft" surface.

Representatives from Ballydoyle are at Epsom to monitor the change in ground, but Aidan O'Brien admitted yesterday that he is "seriously considering" switching Saffron Walden to France and running Tchaikovsky instead at Epsom.

"I would have to be worried. It is lashing rain at Epsom and we know that Saffron Walden is much better on better ground. Both colts are in both races and a switch has to be very seriously considered," O'Brien said yesterday.

Saffron Waldon was yesterday being quoted at a best priced 7 to 1 by Corals. Tchaikovsky, whose first preference had been Chantilly, was still being quoted as high as 66 to 1 for Epsom yesterday.

O'Brien added yesterday evening: "At the moment we are not sure what is going to happen, but we will be discussing it at length tonight and we have to make our minds up in the morning. I wouldn't like to rate Saffron Walden's chances of running but we have people at Epsom to keep an eye on things."

The belief in Ballydoyle is that Tchaikovsky will handle very soft ground better than Saffron Walden, and O'Brien reports that the going at Chantilly is good, with watering taking place.

Tchaikovsky, like Saffron Walden, is a son of Sadler's Wells and has run just three times to date. He won his only start as a two-year-old by a short head at the Curragh, won a three-horse race easily at Gowran in April and was a length and a half runner-up to Port Bayou in the Derrinstown Derby Trial at Leopardstown on May 9th.

The weather forecast will be more suitable for O'Brien's two contenders in tomorrow's Oaks, Sunspangled and Crystal Downs. Both fillies are winners with cut in the going but Michael Kinane decided last night that he will ride Sunpangled.