Renault boss Flavio Briatore fears rivals Ferrari will gain an unfair advantage when Formula One teams switch to just one tyre supplier next season.
Briatore wants a return to slick tyres
Bridgestone - which has supplied Ferrari since 1999 - will be F1's sole tyre manufacturers from 2007 as F1 chiefs seek to lower cars' speeds.
Briatore said: "I believe we need to be worried, absolutely.
"If we are all on Bridgestone next year, then if you use them already surely you have an advantage."
Renault and Ferrari's other main rivals have all used Michelin tyres since 2002, but the French company is pulling out at the end of the current season.
Briatore said he supports the FIA's aims but is concerned at the possible advantage that may accrue to Ferrari.
"I think it is the right way because for a million reasons we want to slow down the car," he said.
"(FIA president) Max (Mosley) had the possibility to control the speed of the car through the tyres, it's cheaper for us than to go to the chassis.
"But we need to be fair. We need to make sure that somebody working with Bridgestone in the last five years or whatever does not have any advantage."
Briatore said he would be delighted to see the untreaded slick tyres of old, which could return in 2008 as part of a far greater overhaul of the rules, after the expiry of the current contracts that bind the teams to the sport.
F1 has used tyres with circumferential grooves since 1998 in an attempt to control speeds.
Briatore said: "Whatever we do, we need to do it quickly because we need to design the car.
"I am completely open to whatever it is. We need to be correct and we need to make sure that nobody has any advantage. Only that."