F1's teams face a strategy dilemma at the Belgian GP, with unexpectedly high temperatures at Spa causing high tyre degradation.
With track temperatures of over 40 degrees on Friday, drivers found tyre management a challenge around the demanding 7km lap. The warm weather has continued into Saturday - and Pirelli believe this creates a conundrum for leading teams in qualifying.
"One interesting point will be to see if anybody is trying to qualify in Q2 with the soft tyre," said Pirelli's racing manager Mario Isola. "That means starting the race with the soft.
"Of course, somebody has to use the supersoft but that means a very short stint at the beginning. In P2 with fuel tanks when they usually try to do a long run, the degradation was very high. So it is something they have to consider."
F1's rules dictate that the top 10 qualifiers must start the race on the tyres they set their quickest time on in the second stage of qualifying, Q2. That is usually the fastest tyre available, but teams were struggling to extract performance from that compound, the supersoft, in practice across a whole lap of Spa.
If teams start on the supersofts for Sunday's race, then they are likely to make their first tyre stop inside the opening laps and drop back into the midfield pack.
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"With the supersofts, if it's lasting for five or six laps, it's not enough," added Isola. "We know the medium is slower but if the degradation is much lower, it becomes a possible compound for the race.
"With these conditions, we have quite high degradation with all the three compounds and this affects strategies. Teams must be flexible to adapt the strategy from what they see in the race."
Teams selected their allocation of tyres for the Belgian weekend several months ago and a number of teams - including Ferrari and Williams - have selected seven sets of supersoft tyres out of 13 sets available.
Asked if tyre selection would prove more decisive than any race so far this season, McLaren's Jenson Button said: "I think so.
"There'll be quite a few people comparing the soft and supersoft to see what's going to be quicker over a full lap.
"It's 30 degrees ambient, 48-50 degrees on the track, is the supersoft going to do a whole lap? It's a long circuit.
"So it'll be interesting to see which one is quicker over a lap. You'll see a lot of quicker cars doing soft tyre laps in Q2."