Sep.8 (GMM/ Ferrari is now leaving Williams behind in the 2015 pecking order, and the British team knows why.

“It is easy to explain,” said Williams technical boss Pat Symonds.

At Monza, while Felipe Massa and Valtteri Bottas battled hard to the line for third and fourth, Ferrari’s Sebastian Vettel finished a full 22 seconds clear of the pair.

“Ferrari has a very big budget; much bigger than ours,” Symonds told Brazil’s Globo.

“They made a huge investment to make a better chassis but especially a better power unit, which was their biggest problem in 2014,” he added.

Brazilian Massa agrees, saying Ferrari’s latest engine upgrade was obviously better as it made its debut at Monza.

“Now it’s as competitive as our Mercedes (engine),” he said. “And on a track like Monza the engine makes a tremendous difference.

“Each race gets harder for us, as they continue to improve their car,” added Massa.