Mercedes technical director James Allison has described the moments that led to the tyre call between Lewis Hamilton and Valtteri Bottas ahead of the closing stages of Portuguese Grand Prix qualifying as "tense".
With Pirelli's medium-compound rubber proving more beneficial than the soft, Hamilton eventually shaved pole ahead of his team-mate courtesy of a second timed lap on the yellow-banded tyre compared to the one from the Finn.
Allison has conceded the call that led to the six-time F1 champion claiming the 97th pole position of his F1 career was not the easiest.
“If you had been in our garage in the dying minutes of Q3 you would understand very well why Valtteri took a different approach to Lewis," said Hamilton. "It's because we didn’t know what was the right thing to do.
"It was a very unusual set of circumstances with a tyre that was proving a little recalcitrant and where it was difficult to get the best out of that soft tyre in qualifying.
"We had found in the second qualifying session that the medium tyre actually gave us our best lap so far of the qualifying session and so when we were going into Q3, when it was proving pretty tight on the soft rubber, we were thinking, 'Well, we've got a brand-new set of mediums still sitting in the garage on heat, why don’t we use that?'
"But that's not the normal pattern. Normally you choose the softest rubber, and so we were sort of slightly off-kilter anyway contemplating using this medium rubber. And then if you are going to use the medium rubber, what's the best way to use it?
"Do you just go out and hit it once with one flying lap, one lap of fuel in the car and, therefore, minimise the mass of the car?
"Or do you give yourself two goes at it and have a chance to get the tyre maybe a little bit warmer on a track where it was proving difficult to get the tyres up to temperature anyway and on a compound that is a bit stiffer, the medium than the soft, and where it might prove awkward to get it really, really happy in its temperature window?"
With the two options offered to both drivers, Allison has confirmed they "chose a different path", which proved the difference.
"I think Lewis chose two laps because in Q2 when he was on the medium tyre, that had been his experience," added Allison. "He felt that he got better performance later.
"Whereas Valtteri had hit Q2 with the medium tyre, hit it on the first lap and got an absolutely brilliant lap out of it. He chose that in Q3 as his best shot.
"Lewis chose the other path and ultimately Lewis just shaded it, but it was a really, really difficult choice where we placed it in the drivers' hands making that decision and it was quite a tense period in the garage while they were weighing that up and while the clock was ticking down.”
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