by Essential Sports

The double world champion said: "Honestly I think it's difficult, because although there are going to be completely new rules. Next year there could be changes, but I've never seen a car that's fighting at the back one year then sweep the field the next.

"It's always step by step. So it's hard to close the gap, whether it's the aerodynamics, the engine, or the tyres. Whatever our problems are, we'd have to work very hard to close that gap.

"But, to be honest, it's going to be difficult to move ahead of them (top teams), and to make a car that will be superior to theirs."

Alonso also revealed that he is happier at Renault than he would have been if he'd chosen to stay at McLaren.

He said: "I'm (saying that) based on the last few races of the past season, when I was finishing fourth and fifth.

"And that's not what I expected. This year I'm still finishing fourth and fifth but with a team who really want me to achieve that result."