The Formula One drivers' title battle between Renault's Fernando Alonso and Ferrari's Michael Schumacher is in the hands of the tyre makers as much as the lap of the gods.
After another full-on fight between the two champions in Turkey, Alonso left Istanbul with a 12-point lead but recognising thatanything could happen in the last four races.
The tyres, said the world champion, could make or break both men's dreams.
"I think we are in Michelin and Bridgestone's hands because at the end of the day, I think the cars are at their maximum development now," the Spaniard said.
"In the last part of the championship, I don't think you can find extra tenths or two tenths (of a second) in the car, while the tyres can give you more than half a second.
"So I think that...the tyres will be the deciding point in the championship."
Both Michelin-shod Renault and Bridgestone-equipped Ferrari have a busy test schedule over the coming week before the Italian Grand Prix, Ferrari's home race, at Monza.
After Monza there will be two more tests for Renault while Ferrari are likely to be using their private Fiorano test facility to the maximum.
Renault have a more powerful engine and new developments coming in for Monza and remain confident, despite their constructors' lead being whittled down to two points.
"It's still really close, we always said it would be," said Renault head of engineering Pat Symonds as he left the Istanbul Park circuit on Sunday.
"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."
Alonso finished second in Turkey, with Schumacher third after a safety car interlude allowed the Spaniard to get past the seven-times champion in the pits in a race won by Ferrari's Felipe Massa.
