Christian Horner has described Barcelona as a "whole new challenge" for Red Bull and Ferrari as their championship fight heats up during the early stages of the season.
After the first five races, Ferrari hold a slender six-point lead over Red Bull in the Constructors' standings, with Charles Leclerc sitting 19 clear of reigning World Champion Max Verstappen in the Drivers' standings.
While Leclerc took victory in Bahrain and Australia, where Verstappen suffered retirements, the Dutchman has won every race he has finished so far.
A new challenge for Red Bull and Ferrari in Spain
As the F1 paddock moves on to the Circuit de Barcelona-Catalunya, Red Bull team boss Horner expects Ferrari's inherent advantage through high-speed corners to present a major challenge.
"It's been nip and tuck," Horner told media, including RacingNews365.com, as he assessed the battle with Ferrari so far this season.
"Barcelona is a whole new challenge [with] high-speed corners, [and] we know Ferrari is strong in that area."
Ferrari will be looking to reinforce this strength with updates to the floor and diffuser on the F1-75, though Red Bull are set to introduce further weight-saving measures on the RB18.
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Red Bull's main advantage is on the straights
With Ferrari making the most of high-speed corners, Red Bull have often found themselves holding the advantage on the straights.
This was evident last time out at the Miami International Autodrome, where Verstappen held off Charles Leclerc in a thrilling late scrap that ebbed and flowed over the course of the lap.
"I think we had just enough straight-line speed to be able to defend; we picked the right balance in terms of set-up and straight-line speed," added Horner.
Horner then shed some more light on why Red Bull are enjoying improved top-end speed this season.
"Obviously it's very different this year with the set-up we're running," he said, pointing to the overhauled technical regulations.
"There's no rake (angle) in the car, essentially, so we've developed a car that has good straight-line speed, and we've seen that at pretty much every race this year."
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