Charles Leclerc says Ferrari is struggling to understand a "weird" performance discrepancy between Pirelli's soft and medium tyre that could catch out the Scuderia in qualifying.
In Friday's FP1 session, all teams relied exclusively on the red-rimmed soft compound for their initial set-up work in the morning, sparing therefore their medium and hard allocations which will likely be required for Sunday's minimum two-stop race.
A direct comparison in the afternoon between the soft and medium tyre revealed hardly any performance difference for most teams, implying that drivers are likely to give priority to the medium rubber in Q2.
However, Ferrari noted in FP2 a shortfall in performance when running on the medium, a disparity that had Leclerc scratching his head.
"It was a bit more difficult than last Friday, to be honest," said Leclerc, who set the seventh fastest lap in FP2.
"We are still working quite hard to try and understand a bit more these tyres.
"We had quite a big step of grip in between the medium and the soft, which is not the case for the others, so we need to understand why we're a bit too slow on the medium.
"That's what's a bit weird today for us, because normally we struggle to use the softer tyres with our car, but today was a bit different, and we struggled to use the medium tyre more than the others, and we had quite a big step from medium to the soft."
Leclerc doesn't believe the difference is rooted in Pirelli's decision to run higher pressures this weekend compared to last week's first round at Silverstone.
"It hasn't changed much, obviously the tyre pressure has changed for everyone, now we need to understand," he said.
"The car balance feels actually pretty good, it's just the overall performance that is not as good as I would have hoped on the medium, which to be honest I don't have any answers to it for now.
"I think the lack of performance on the medium is where we need to work the most because it's going to be important.
"Many guys will try to go through on Q2 with a medium tyre, and we need to be competitive on these tyres to have a chance, so we need to put our effort onto that.
"I think it will be very interesting to see tomorrow after qualifying, which will be the compound for everyone to start on, but it will be an interesting race with many different strategies. And let's see if it pays off, if we are taking a gamble."
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