The 2005 Formula One season could be Ferrari's toughest challenge of the Michael Schumacher era, according to the champions' race technical manager Nigel Stepney.
"The changes this winter are bigger than anything we've had to deal with before - certainly since 1994-95," Stepney told British weekly Autosport magazine.
"We are the only major team on Bridgestone tyres, when all our rivals are with Michelin. I'm certain that will give them an advantage," added the Briton. "This will be our biggest challenge yet."
Ferrari have won the last six constructors' titles in a row while seven times champion Schumacher has reigned for the last five years.
Last year the Italian team won 15 of the 18 races, Schumacher taking 13 of them in a dominant return after a hard-fought 2003 season that went down to the wire. The regulations have been changed for 2005 however to slow the cars down for safety reasons.
The new measures include limiting each driver to just two sets of tyres per race weekend and a stipulation that engines must last for two races rather than just one at present. There are also significant aerodynamic changes to the cars.
The tyre changes mean the manufacturers will have to develop new 'long-life' compounds to last for around 350km rather than 100 this year.
Bridgestone technical manager Hisao Suganuma said having just Ferrari to do long-distance testing put them at a disadvantage.
"Our rival (Michelin) will have seven competitive teams developing different compounds and constructions. That is bound to give them a bigger pool of data to work with," said the Japanese.
The season starts in Australia on March 6.