Lando Norris's stunning long run on the second day of 2025 pre-season testing in Bahrain has left rivals in no doubt that McLaren has made a step with its new Formula 1 car.
That race sim, run at a similar time to Ferrari's Charles Leclerc and Mercedes' Kimi Antonelli on Thursday evening, produced some eye-watering numbers with Norris over a second quicker per lap quicker in the final stint, and 31s quicker than Leclerc across three combined stints.
Ahead of a season that has been tipped to be one of the closest ever, that is the kind of advantage actually more akin to the edge Red Bull had 12 months ago before it smashed the start of the 2024 season.
But while the raw numbers tell one story, there are some caveats that have left McLaren's rivals unsure whether that margin is actually a true picture or flattered by circumstance.
From McLaren's perspective, it is far from getting excited about what it has seen, as it actually feels that what team principal Andrea Stella calls a "unique" set of circumstances in Bahrain has clouded things.
The first element is that McLaren's race sim was not done with the same tyre strategy as its main rivals, Norris running a C3/C2/C1 order while Antonelli and Leclerc did it with a C3/C1/C2.
So what we cannot separate is how much of the final numbers were down to pure car form and how much was down to the tyres, if it is shown that Norris had the better rub of tyre performance.
Stella suggested that McLaren had simply cycled through the three compounds in a bid to better understand the characteristics of each one, rather than chasing the optimum.
"In terms of tyre choice, our long run was just aimed at testing the three compounds and seeing how they behave," he said.
"I think everyone, even if they changed the order, wanted to achieve the same - just see what are the right compounds for the race, considering that Pirelli have changed the nature of the compounds compared to what we had last year. And they do seem to be different."
There's differing engine modes to consider too. Mark Hughes found that at the end of the pit straight Norris was 10km/h faster on his eye-catching final stint than his middle one, while on the run to Turn 4 he is at 291km/h compared to his previous 286km/h speed.
The biggest note of caution from McLaren about reading too much into Norris's impressive race run came from the unexpected weather that has impacted the Bahrain test.
Drastically cooler conditions - with temperatures around 20°C cooler than is normal for the grand prix - mean how cars are running around Sakhir is a world away from how things will be in full-on race conditions.
As Stella said: "We are testing long runs in conditions which are pretty unique. It's cold Tarmac, cold air temperature."
A warmer track surface would expose any potential weaknesses cars may have with tyre degradation. So we cannot know if McLaren - a team that has traditionally struggled in Bahrain - has been flattered by what we have seen.
This is why Stella thought reading too much into a single race run like Norris's on Thursday evening would be a mistake.
"Overall it's good information obviously when you go through long runs and race simulations, but every information we get needs to be taken with some care," he explained.
"We need to be careful and it's very particular. When we go to the early races of the season, the kind of stress on the tyres, the requirement in terms of the interaction between the car and tyres will be completely different.
"The indications here in Bahrain seem to say that the car interacts well with the tyres but in a very specific, and I would say special, regime like we have in these days here in Bahrain."
Stella isn't getting complacent over McLaren seeming more settled at a traditional bogey track for its cars either.
"This year the car seems to have adapted to the Bahrain requirements a bit better than in previous years but the conditions are so unique that they may be masking some of the traditional issues that we may be having," he said.
"Certainly they are making for instance traction requirements, stability, much easier because the laptimes are incredibly fast and I think we're seeing the good side of what the operating conditions can be for an F1 car. Once we come here for the race, it will be more difficult.
"More difficult for everyone and certainly more difficult for us."
Rear instability?
Another area of intrigue surrounding the McLaren has been comments Norris made after his first day's running of there being a rear end weakness.
While no car is ever perfect, his suggestion that things were not as strong in this area as the team would have liked prompted some raised eyebrows.
But as Stella has suggested, while Norris's remarks may have been based on a legitimate early feel for the car, they are perhaps not unusual for any team that wants to be quick around Bahrain.
"The comments of Lando related to the rear instability were fair," said Stella.
"At the same time when you come to Bahrain, I would be very surprised that you don't have a rear end limitation and traction limitation. Somehow these limitations are inherent to the circuit at which we are operating."
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With the team having worked a lot on delivering a stronger rear end, Stella felt that things were actually not that far off what was wanted.
And he said that the only time such rear-end issues had even been wiped away completely was by radical ideas such as the blown floors that were commonplace in the early 2010s - as he referenced an experience he had when he worked at Ferrari.
"We think we have improved from this point of view, but you improve always by a quantity that is never going to make these kind of problems disappear," he explained.
"The only time in which I saw something changing as dramatically as like, 'There are no problems with traction anymore, now the car pushes in the traction' is when we had the exhaust effect.
"When you go back to 2011, 2012, I was at my previous team and we introduced the exhaust effect from one session to the other. The car was like, 'Not a problem with traction anymore!' That's a dramatic change of aerodynamic behaviour.
"But within what you can do inside the scope of the regulations, which is fixed, then you're always going to suffer the same limitations. Ultimately you need to try and reduce those limitations more and more."
