Lotus will inevitably fall behind as a consequence of missing the first Formula 1 test of the 2014 season, according to Renault's deputy managing director Rob White.
Lotus looks set to be the only team that will be absent from the Jerez test next week, having announced earlier this month that attending it was "not ideal" for its build and development programme.
The team was sure others would miss the test, but all its rivals have confirmed they will be at Jerez.
Lotus has suggested that its programme would not be hurt much because Red Bull, Toro Rosso and Caterham also use the Renault engine.
While White concedes there is data that can be shared with Lotus to make up for missing the test, he believes the team will lose valuable time needed to adapt the engine to the chassis.
"The fundamental power unit is identical, but each installation is unique," said White.
"The objectives for the first test are to fully validate the power unit in its environment. It is the first time that you can bring the whole thing together and turn it on - you haven't got the chassis combined at the factory.
"We do a great deal to simulate as much as we can, but ahead of the fire-up we haven't ever brought together every single piece of sub-system and system in the exact configuration that it will be, in that car.
"So the stuff that is, if you like, shareable and shared between the teams is the stuff that pertains direct to the power unit, not the stuff that pertains to its particular environment.
"Clearly anybody that isn't able to run at Jerez will be a little bit behind and that includes the power unit side of the equation."
F1 teams will have just 12 days of testing before the season kicks off in Australia on March 16.
White admits that, given the big regulation changes coming into play this year, the formbook could fluctuate a lot during the first races of the season.
"At the beginning there will be a rapidly shifting situation," he said.
"I don't think it will be possible to evaluate performance in a week's time, at the end of the Jerez test, and certainly the season needs time to settle down.
"There is a lot of uncertainty about what the outcome will be. It will be about checking out where the performance of the car lies relative to the design assumptions being made."