Strategy for the Spanish Grand Prix is delicately poised between a one-stop and a two-stop race.
If Mercedes, which starts the race with its two cars on the front row, is able to pull a gap on the rest of the field, they are likely to opt for a risk-averse one-stop. Only a much closer race in which one of the cars behind poses a genuine threat of an undercut is likely to take them off that course.
The way to tell the difference between a one-stop and two-stop strategy will be the timing and tyre choice at the first stop. The pit stop window for a two-stop opens on lap 13 and runs to around lap 22 and will likely see drivers move to the medium compound whereas a one-stop will likely happen between lap 16 and 24 with a switch from softs to hards. The pit stop window for a second stop is likely to sit between laps 43 and 53 and will see a return to the soft compound for a sprint to the finish.
Looking at the available tyre compounds, it is clear Mercedes is angling towards a one-stop as it has no fresh soft tyres left in its selection and a fresh set of hards. Max Verstappen, starting fourth, has a fresh set of mediums and softs available to him and could, in theory, attempt a two stopper to mix things up. The only problem with two-stopping is that it is quite hard to overtake at Barcelona and it will require the team to find a gap in the traffic to drop cars into so as not to lose time behind a slower one-stopper. So if Verstappen makes a good start and is up to third at the time of the first pit stops, Red Bull is more likely to play conservative and opt for a one-stop to maintain its position ahead of Ferrari.
The timing of the first stop will largely depend on the degradation suffered on the softs. Temperatures look like they will be hotter than Friday, so drivers starting on the softs will have to be very kind to their rubber in the opening stint to make the marginal one-stop work.
Outside the top ten, drivers have the luxury of starting on the mediums as they are not beholden to their Q2 tyre choice. That makes a one-stop much easier in terms of managing tyre degradation and adds extra flexibility should a Safety Car come out.