A "surprising" gap between the hypersoft and the ultrasoft tyre at the Abu Dhabi Grand Prix makes it unlikely the top teams will get through Q2 on the harder tyres, reckons Pirelli.
The large speed advantage that Mercedes, Ferrari and Red Bull have enjoyed over the rest of the field has meant that at times this year they have had the luxury of being able to pick a more durable tyre to progress from Q2, and therefore start the race on.
However, Pirelli's head of racing Mario Isola says that such a plan will not work at the Yas Marina because of the performance difference between the two softest tyres.
"The biggest surprise is that the hypersoft is a lot quicker," explained Isola after the first day of running.
"We were estimating a delta lap time of 0.9-1 second, which is in line with last year - and last year we tested the older range here in Abu Dhabi.
"It actually seems it is a bit more, and in the range of 1.3 - 1.4 seconds. It means that for qualifying, it is very difficult to have somebody trying to go through Q2 with the ultrasoft.
"While it is true that the top six are very close, it is also true that 1.3 seconds is a lot so I think nobody is going to take the risk to qualify with the ultrasoft."
Although Pirelli thinks the top three teams will find it hard to get through without using the hypersoft, Haas driver Romain Grosjean is not so convinced.
Having led the best-of-the-rest battle in practice, he says midfield teams will certainly be forced into using the hypersofts in Q2 but thinks the top teams may be able to sneak through on ultras.
"The ultrasoft is very slow from what we've seen today," said Grosjean.
"So, it doesn't look like unless you are in one of the top cars you can go through with the ultra to Q3.
"But in Mexico some cars started on hypersofts and did a good job, finished well, so we will have to do our best to do that."
Isola says that if teams are forced to start on the hypersoft, then the first stint of the race could be as short as 15 laps before drivers switch over to the supersoft.
"If they start on the hypersoft then what we have seen today with the heavy car and with heavy tank there is some graining," he said.
"The hypersoft stint will not be very long - probably not more than 15 laps. And then it is possible that they switch to the supersoft to go to the end.
"It is the one that today showed a better consistency and the delta between the supersoft and ultrasoft is very small - 0.2 seconds - and that means that for the race, if they choose the supersoft, it is not a big disadvantage."