Fernando Alonso believes the next three grands prix in Spain, Monaco and Turkey will be decisive to see if Renault can recover from a poor start to the season and fight for the title.
The Spaniard and his team have scored just five points in the first four races, as the R29 car has not proved fast enough to fight near the top.
Alonso says the updates the teams will bring in the next three races are likely to determine the course of the season.
"I think the next three races are quite important - Spain, Monaco and Turkey," said Alonso, who finished in eighth position at the Bahrain Grand Prix last Sunday.
"I think more or less, all the teams will bring all the big parts for the next three races.
"Some of the teams will put everything in Barcelona, some of them will have something in Monaco and the last couple of teams will put what they have on in Turkey.
"So after that, we will see who is challenging for the championship, and who is challenging for podiums and who is completely out of everything."
The Renault driver also said Brawn and Red Bull, the two teams who have won races so far this year, have all the resources to stay ahead, despite not being backed by a major manufacturer.
"We will see. I think two private teams are leading now, but they are big teams," he said. "We cannot forget that sometimes we call them small teams, and they are not so small. Red Bull and Brawn have the resources, maybe more than even Renault, and more facilities than Renault.
"This is something that we need to be aware of, and it is a shame for Renault and Mercedes that they spent the money, they keep developing the engines and then they gave to Brawn and Red Bull and they fight for the championship - but that is the way it is."