Christian Horner has admitted that, as things stand, Mercedes appear to have an edge over Red Bull in terms of race pace.
While Red Bull, particularly in the hands of Max Verstappen, are very strong over a single lap, their race pace in Portugal and Spain simply wasn't enough to challenge Mercedes properly for victory.
Having been hauled in by an aggressive two stop strategy from Lewis Hamilton in Spain, Horner said that the reigning Champions just seem to have an edge in terms of tyre wear and overall laptime during a race.
"I think the Mercedes, we've seen it since Bahrain, I think that their race pace has been better than ours at each Grand Prix that we've seen so far," Horner told media, including RacingNews365.com
"I think that their degradation has been better than ours. So we knew these last two circuits would play to their strengths so they've done that but we're an awful lot closer than we have been and I think if we can find some more race pace, it's still very, very tight between the two cars.
"Testing was a three day test, and they didn't show their true potential at that test and we've seen that from Bahrain, they've been right there particularly on race pace."
Red Bull traditionally don't start the season particularly well, and instead become more competitive as the year progresses thanks to a strong development route. For 2021, this could be different, as teams abandon the current cars in favour of the widespread regulation changes for next season.
Horner said that smart development will be the key to beating Mercedes this season, and is hopeful that the team's usual strong upward performance continues this year.
"Of course, it is going to be about developing and developing efficiently, developing within the constraints of designing a new car for next year as well," Horner explained.
"So that poses its own challenge. A 23 race calendar is a marathon season. And we need to make sure that we're there for the second half. So that that's been generally where we've been stronger."