F1MATHS: Eight seconds separate the one- and two-stop strategies at Spa

Pirelli expects the Belgian Grand Prix to be decided by a one-stop strategy after Saturday's running at Spa-Francorchamps confirmed that tyre degradation is low enough to make a single pit stop the fastest option.

Following qualifying, Pirelli indicated that all the available data points towards teams completing the 44-lap race with just one stop, with the choice of starting tyre likely to depend on the number of new sets each team has retained.

"Everything suggests that tomorrow's [today's] race will be a one-stop, with strategy mainly determined by the new tyre sets available to each team," Marrafuschi explained.

"The opening stint could be completed on either the Medium or the Soft, depending on which new sets teams have chosen to keep."

According to Pirelli's simulations, the conventional strategy is to start on the medium C3 compound before switching to the hard C2 tyre between laps 17 and 23.

"The top teams may start on the C3 before switching to the Hard between laps 17 and 23," Marrafuschi said. "Those who have saved a new set of C4 could instead use it at the start, bringing their stop forward into the 14 to 20 lap window."

While the medium tyre appears to be the default choice, Pirelli believes the soft C4 compound has become an increasingly attractive race tyre after showing stronger-than-expected performance throughout practice and qualifying.

"The Soft was extensively tested during the first hour of free practice and, on some cars, appears to give drivers better feedback under braking," Marrafuschi noted. "For this reason, it could be preferred, also thanks to the grip advantage it offers."

The alternative two-stop strategy remains available, but Pirelli estimates it carries a significant time penalty.

"Two-stop strategies are approximately eight to ten seconds slower," Marrafuschi said. "Possible options include Soft-Hard-Hard and Soft-Hard-Medium."

However, the Italian manufacturer believes race interruptions could still influence strategic decisions. Several teams deliberately retained an additional set of hard tyres in anticipation of possible Safety Cars or other neutralisations.

"As already noted yesterday, some teams have kept an additional set of C2 as a precaution, which could prove useful to have a fresh tyre available in the event of a neutralisation."

Saturday's running also confirmed that tyre performance closely matched Pirelli's pre-event simulations. Despite warmer conditions than during final practice, with track temperatures rising from 36°C in FP3 to 38.5°C during qualifying, tyre behaviour remained predictable.

"Tyre behaviour is in line with our expectations," Marrafuschi said. "Lap times are also now close to simulations, with just a one tenth gap between the pole time and our projections. The track has evolved quickly and thermal degradation on the rear axle is now the only factor that will need to be taken into account during the race."

Mercedes' Andrea Kimi Antonelli claimed pole position with a lap of 1:44.361, more than three tenths faster than Max Verstappen, while Lando Norris qualified third.

Although qualifying pace demonstrated the competitiveness of the soft compound over a single lap, Sunday's race is expected to become a strategic contest, with teams weighing the soft tyre's superior grip against the longer opening stint offered by the medium.

Unless weather or a Safety Car intervention changes the picture, Pirelli expects the overwhelming majority of the field to commit to a one-stop race, as the eight-to-ten-second deficit associated with two stops is simply too large to overcome under normal racing conditions.