William Haggas is monitoring the weather closely for intended weekend runners Addeybb and Young Rascal.
Addeybb has been declared for the Qipco Irish Champion Stakes at Leopardstown on Saturday, with his stablemate due to contest the Prix Niel at ParisLongchamp 23 hours later.
Winner of his first two starts this season, Addeybb was last seen finishing eighth in the Lockinge Stakes at Newbury in May.
Haggas told Press Association Sport: "I'm very concerned that there hasn't been enough rain. He has been in great form and he needs to run.
"The last thing I want to do is jar him up on fast ground and not have him for the autumn. I think stepping him up in trip will suit him.
"He is not going to win a Group One over a mile unless it is very soft or heavy ground."
Young Rascal was a leading contender for Investec Derby honours after winning the Chester Vase. He was seventh of 12 to Masar in the premier Classc and has not run since.
Haggas said: "He needs rain and it has not rained at all, but he has been declared. I need to speak to Mr (Bernard Cantor, owner). If it looks like being dry we will swerve it, but he is another that needs a run.
"If he doesn't go to France he will go to Newbury for what was the Arc trial.
He added: "He took the Derby very hard and it has been a battle coming back and hard work getting him right, as it bottomed him out.
"For some reason he just wasn't the same after Epsom. I wanted to run him in the Voltigeur, but it was too quick. I want to run him in the Niel, but I don't want to go back to where we were after the Derby. "