When Lando Norris wondered aloud: "F**k's sake, how did we not win this? We should have won..." after the Miami Grand Prix, it reflected the fact Mercedes was once again beatable yet continued its perfect start to the 2026 Formula 1 season.

Norris's almost-incredulous rhetorical question did not need an answer, but it has one: McLaren was gazumped by Mercedes, which won a fourth straight grand prix the hard way.

McLaren and Mercedes inevitably claimed the other was slightly faster in Miami, but they were close enough that it did not matter which one really had a tenth or two in hand. McLaren's big upgrade package, and Mercedes only bringing minor new parts, addressed a large chunk of the car deficit last year's world champion had to its engine supplier.

This turned it from opportunistic pretender to out-and-out contender: hence Norris winning Saturday's sprint race from pole, helped by Mercedes not optimising its energy deployment until the middle of the weekend.

"We overcomplicated our life with where we wanted to go with the car and the power unit in terms of energy management," said Mercedes team principal Toto Wolff.

"And we realised that we just needed to go back to something more conventional. So, we lost three, four tenths against McLaren and most of the others in sector one.

"We fixed that and that brought the performance back."

Norris could, and probably should, have completed the double for McLaren in the grand prix. It was initially led by Ferrari's Charles Leclerc, briefly interrupted by Antonelli, before Norris got ahead of both in the opening stint and started to take control.

But even on a relatively weaker weekend, Mercedes is too fast to be discounted.

It is still yet to end an opening lap in the lead this season, despite starting from pole at every race, and this trend of forfeiting track position continued in the United States.

Only this time it was not the brute force of its pace advantage, or a bit of safety car fortune, that reinstated one of its cars into the lead again: it was better execution in the crucial pitstop phase.

"We just got undercut," Norris said bluntly. "There's no excuses other than that.

"We got undercut. We should have boxed first."

With the threat of rain looming but never quite materialising, Mercedes decided to pull the pin on an earlier stop as soon as it could be reasonably confident that intermediate tyres would not be needed.

The gap to Norris had stabilised at around two seconds, and a pass on-track in a steady-state race to the finish seemed unlikely as the McLaren - like last year - looked after its tyres well.

Knowing the value of the undercut, Mercedes pitted as soon as it looked like even an immediate response from McLaren would be too late.

And so it was. Mercedes' timing was right, so was its 2.2-second pitstop. Antonelli aced his inlap and his outlap, Norris pit the lap immediately after - and although Norris emerged from the actual pit exit ahead, Antonelli was able to nip by on the run to Turn 4.

McLaren team principal Andrea Stella said it was an example of how "execution, adaptation, optimisation" can become the deciding factors when the margins are so close between cars.

"The timing of the pitstop was the decisive factor, but at the same time we should be careful that we don't only see it from a strategic point of view," said Stella.

"Because you have the timing of the pitstop, which is a strategic element, but then we lost time in the pitlane for instance, which is an execution aspect.

"It is a combination of the driver stopping, the pitstop itself, and we lost some time in the inlap as well."

Antonelli was also swift at clearing Max Verstappen's Red Bull with its old hard tyres shortly after passing Norris.

And, with track position secured, he was able to keep Norris more or less at arm's length for the rest of the race.

But had those roles been reversed, the same probably would have gone for Norris.

"We were fighting a faster car than us, but perhaps if we had kept Lando in the lead, we could have led it to the finish," said Stella.

"When you are in the lead, and you are in condition to retain the lead like Lando was today in the first stint, then you definitely have a chance to win it."

McLaren is adamant Mercedes still has a couple of tenths of a second's advantage, but it was beatable in Miami.

What's now to be determined is whether Mercedes' own upgrades will move it clear again or if it is going to face this kind of stern challenge elsewhere.

"The fact we made such a big step this weekend is great to see and I'm very proud of the team, and all the work that's been put in has paid off immediately," said Norris.

"But you always have to look at it and ask yourself the question: do you feel like you maximised everything today? And I’m unsure about that.

"I know he came and passed me on track because he had just the warmer tyres out of Turn 2, but we should have just never been in that situation in the first place.

"I'm not saying we would have won the race because I think Kimi drove an excellent race and his pace was very strong. So, he might have still passed me later on in the second stint if we boxed earlier.

"But at least we would have given ourselves a fighting chance, and we didn't. So, I'm a little bit disappointed by that."