Alonso is 12 points ahead of Schumacher with four races left

World champion Alonso and Michael Schumacher are engaged in a fascinating tussle for the drivers' championship.

And the Spaniard said: "I think we are in Michelin and Bridgestone's hands because at the end of the day, the cars are at their maximum development now.

"The tyres can give you more than half a second, so I think they will be the deciding point."

Alonso has a 12-point lead over Schumacher heading into the last four races, while Alonso's Renault team lead Schumacher's Ferrari by just two points.

Both Renault, who run on Michelin tyres, and Ferrari, with Bridgestones, plan a heavy testing schedule over the coming week ahead of the Italian Grand Prix in Monza.

"It's still really close, we always said it would be," said Renault head of engineering Pat Symonds.

"I'm really pleased we are getting some testing in because it's been a struggle for the last few weeks, particularly with the mass damper coming off and everything.

"Michelin have got a hell of a programme for next week so there's a lot to do there and I think when we finish that programme we will have a better idea of where we stand. But I think it's going to be close in every race."