Christian Horner admits Mercedes' victory at the Bahrain Grand Prix will be difficult to take before the next event of the 2021 Formula 1 season in three weeks.
Max Verstappen was on course for victory but overtook Lewis Hamilton off the track and yielded the position to the Mercedes driver with four laps remaining. Despite Verstappen's best efforts, he was unable to reclaim the lead.
Horner feels the first half of the race was key to the end result of the Grand Prix.
"Mercedes had very strong pace at the beginning of the race," Horner told RacingNews365.com and other members of the media.
"We couldn't create a gap to cover Mercedes, their degradation was, impressive so Verstappen could never get more than two seconds clear of Hamilton.
"Going into the race, we'd very much fixed our strategy on a on a two stop. On the last stop, we stayed out 10 laps longer and so we had a better time for the final stint.
"But unfortunately, Hamilton had just enough to be able to, to hold on so tough to lose a race like that but we have to take a lot of positives out of the weekend."
Verstappen was forced to give up the lead and Horner revealed the stewards instructed Red Bull to tell Verstappen to hand the position back to Hamilton.
"Verstappen was very sporting and did that and it was it was frustrating," added Horner. "Hamilton had to just enough to retain his position to the end of the race.
"There's no guarantee we could have got the the five seconds (if Verstappen didn't hand the position back) if that had been the penalty so he did the right thing."
Horner was particularly annoyed at Hamilton's and Valtteri Bottas' consistent abuse of track limits throughout the 56-lap race and wants to ensure the rules are clearer in the future.
"It was frustrating," said Horner. "We could see as soon as Mercedes started to push, they just use that part of the track and we question race control, 'if that's the case, can we do it' because when you're in a nip and tuck battle, there's a tenth of an advantage using that part of the circuit.
"So Mercedes did it lap after lap and the race director then asked them to respect the limits, otherwise, they get a black and white flag."
Verstappen suffered with a differential issue which cost him time in the slow speed corners from the start of the Grand Prix. Horner says Red Bull will need to investigate why they had a differential problem on the RB16B.
"Verstappen was having some issues, we think with the differential in the early part of the race and you could see he wasn't happy," said Horner.
"I think it seemed to compromise his first sector compared to the Mercedes so we need to understand and look into that into that issue further.
"But definitely, he wasn't as happy as he had been in that part of the circuit in the first sector and you can see respectively that was our weakest part of the circuit today."
"The great thing for Formula 1 is it looks like that, we have two teams that are close. I think it was a great race today. A tough race to lose but congratulations to Mercedes and Lewis Hamilton today.
"Hopefully, we can give him a hard race and a hard time at all 23 races of the championship."