Christian Horner expects Red Bull to struggle to keep up with the Mercedes-powered cars during this weekend's Canadian Grand Prix.
After starting the season slowly, Red Bull was clearly the second fastest cars in Spain and Monte Carlo, but according to the Red Bull Team Principal, the characteristics of the Circuit Gilles Villeneuve will suit the Mercedes cars.
The long straights in particular, where the difference in engine power between the Mercedes and Renault engines are the most accentuated, is a cause of concern for Red Bull.
"I think Montreal is going to be a challenging race for us and it will be interesting to see how we fare there," Horner told Autosport.
"Renault is working hard behind the scenes, and we were much, much closer [in Monaco].
"It is the first time we have raced Mercedes this year, and Dan's pace, particularly in the last third of the race, he was the quickest car on the track, so we take a lot of confidence out of that.
"But you go from one extreme to the other: Monaco is all about handling characteristics, the next event is straightline performance, so it is going to be very interesting to see how we fare against the Mercedes- powered teams in Montreal."
While the Renault engines struggled with reliability problems throughout the year, its Head of Trackside Operations Remi Taffin is hopeful that the mechanical updates that will be applied to the power units will contribute to solving from of those issues.
"It will improve performance too because if you can run twice the mileage it's going to be much better for performance because you don't have to limit the drivers or the teams," said Taffin.
"But they won't give us more power - that is not the purpose. Getting rid of any DNFs is a powerful performance advantage."