Fernando Alonso, Aston Martin AMR24, George Russell, Mercedes F1 W15, Sergio Perez, Red Bull Racing RB20, Lewis Hamilton, Mercedes F1 W15, Zhou Guanyu, Stake F1 Team KICK Sauber C44, make a practice start

Formula 1 teams have been left facing some difficult strategy choices for the Brazilian Grand Prix as a host of elements have come together to make things extremely complicated.

A combination of the new track surface, the timing of the sprint race, Pirelli's selections for this weekend and uncertainty over the weather have created a perfect storm where the best route forward is not clear right now.

Of particular concern is the fact that teams cannot be sure which combination of tyres they need to keep back for Sunday's grand prix, because the picture from the opening day of running has not offered a firm answer about degradation and wear levels.

The newly-resurfaced Interlagos circuit seems to offer some decent grip levels, but degradation levels were far from clear because of the huge fluctuations in track temperature caused by the new black asphalt.

Opening practice took place with the track nudging the mid-50Cs, and that opened the door for the tyres to be punished quite a lot, especially when the appearance of graining also contributed to some excessive wear.

As Williams driver Alex Albon said: "It's unbelievable degradation here. This track is made out of sandpaper, so it will make it interesting."

However, things seem more settled down in the late afternoon when sprint qualifying took place, as track temperatures dropped into the 40Cs.

But teams will be aware that Saturday's sprint takes place at 11am local time on Saturday, when track temps will likely be in the upper region.

So, with Pirelli having selected the most aggressive of its tyre compounds for this weekend, and the soft being pretty much a single lap tyre so not suitable for the sprint duration, that will likely nudge teams to having to use a medium or hard on Saturday.

The difficulty with that though is that teams are very tight on the number of sets that they have left.

After sprint qualifying, all the top teams are in the same boat, in having two new hards available, then one new and two used mediums.

So, with indications pointing towards Sunday's grand prix being a two-stop race, teams are going to have to choose where the compromise comes from and where they likely run a used medium.

It is not clear yet whether track temperatures and degradation will mean the best strategy on Sunday is to run medium/hard/medium (which was last year's strategy based on the current tyres being one step softer), or medium/hard/hard.

Both strategies are currently viable and there is only a few seconds of difference between them on paper, although a double medium choice could require more management.

This means if teams burn through one of their new sets of tyres for the sprint, then they will have to run with used mediums in the race.

Normally, a used set of tyres - the mediums will have done a few laps in a qualifying effort during SQ1 or SQ2 is not such a problem - but it could trigger some downside this time around because Brazil's race could be a battle against tyre wear rather than keeping temperatures under control.

And the level of wear appears to be much higher than it is in the past because the new track surface is triggering some graining.

Pirelli's chief engineer Simone Berra said: "We expected this with the new tarmac, with the new surface.

"It's something that is quite usual, especially on the rear right, but it is also the front right inner half of the tread. And this graining level is affecting the acceleration of the wear in some regions."

Berra reckoned there was no perfect way forward right now, as at some point teams on Saturday or Sunday were going to have to go with something that was not ideal.

"They have to make the correct choice," he said. "We know that we were a little bit on the limit in terms of wear life, considering the new asphalt and the new compound selection.

"So, I think it creates a little bit different strategies, because with the new tarmac, the C3 (the current hard) should work quite well, and should have better performance compared to last year, when it was the medium and some teams struggled with.

"The C4 (the current medium) last year was really good, and we've seen this year as well that the C4 is not too bad.

"So, teams have to decide if they prefer to keep the two sets of hard compound, but also to keep some good sets, so not much used, mediums just to switch from one strategy to the other.

"Then we know that on Sunday there is a chance of rain, and this can change also the compound selection for the race. You would rather prefer not to use the hard, for example, and use the medium [in the damp] because of the higher grip level in these kind of conditions.

"Everything is very viable at the moment, and I think it's making the racing interesting."