Red Bull's Max Verstappen topped the first practice session of the season in Bahrain, but team boss Christian Horner reckons Mercedes is looking "pretty ominous" after its pre-season troubles.
Both Valtteri Bottas and Lewis Hamilton clocked in among the top-four in FP1, with the Finn concluding his session 0.298s off Verstappen, a performance that suggested that the Brackley squad's efforts to improve its W12 in the last two weeks have been productive.
And that conclusion wasn't lost on Horner.
"It's always great to see your car at the top of the timesheet," the Red Bull team boss told Sky Sports F1.
"But you know, Mercedes are looking pretty ominous. So we don't take anything for granted. But we're happy with the performance of the car so far."
Verstappen's initial pace confirmed the strength of Red Bull's 2021 package which blends an improved RB16B chassis with Honda's all-new power unit.
"I think, last year, we really understood where some of our weaknesses were," explained Horner.
"We managed to understand what our tools were telling us as well, both the wind tunnel and CFD and some of the correlation issues that we had in replicating what those tools were saying and what we were seeing on track.
"So I think, having understood that, the whole engineering team has worked incredibly hard over the winter. Hopefully, we've got a good starting base that we can then build on through the season."
Horner highlighted an overall trend that has seen teams - including Mercedes - follow this year Red Bull's high rake design philosophy. A direction they have felt compelled to follow as a result of this year's regulation changes that have produced a reduction in downforce.
"It's interesting to see, you know, some of our competitors going higher and higher on rear rake and on rear ride heights when, traditionally, they've stayed very low," said Horner.
"So, hopefully, it's something that we can make good use of and, I really hope that we can have a competitive year this year and put a sustained campaign together."
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