Sainz’s engine switch comes on a weekend where Ferrari is not overly optimistic about its overall form, with the car not as comfortable around the Hungaroring as at other venues.
The Spaniard, who ended second practice one place behind team-mate Charles Leclerc in 12th on the timesheets, said the layout of the track left Ferrari exposed as the run of low and medium speed corners does not especially suit the SF21.
“Unfortunately before coming here, we already knew that we have some weaknesses in our package,” he said. “In our car we know for some certain corners of this circuit it was not going to be particularly good at and we proved it [on Friday].
“In Monaco, we would have never been P11, P10 in a practice session. And unfortunately, as soon as something went in the wrong direction, we found ourselves out of the top 10. It shows we are a lot more vulnerable in this sort of track, it’s not a Monaco.
“We’ll kind of hope that we can recover a bit of pace, and at least try and be on top of the midfield. But it’s not easy, because the Alpine looks very quick, McLaren looks quick, the Aston Martin was very quick also.
“It looks like a very mixed midfield, and it should be a very interesting battle for Q3.”
OPINION: The headlines were dominated by the Italian Grand Prix clash between Max Verstappen and Lewis Hamilton, who had the halo to thank for avoiding potentially serious injury. But two days earlier, Formula 1 had a lucky escape with a Monza pitlane incident that could also have had grave consequences.
With two sprint races under its belt, Formula 1 must now consider its options for them going forward. While they've helped deliver exciting racing on Sundays, the sprints themselves have been somewhat lacking - creating yet another conundrum for F1 to solve...
OPINION: With Valtteri Bottas already signed up for 2022, all eyes are on the race for the second seat at Alfa Romeo next year. Antonio Giovinazzi is the current incumbent, but faces a tough competition from appealing short and long-term prospects
OPINION: Daniel Ricciardo has long been considered one of Formula 1's elite drivers. But his struggles at McLaren since switching from Renault for 2021 have been painful to watch at times. Yet he's recovered to banish those memories with a famous Monza win – built on a critically important foundation
The clash between Max Verstappen and Lewis Hamilton was the major flashpoint the 2021 Italian Grand Prix will be remembered for. Yet by this point, race leader Daniel Ricciardo had already done the hard work that would put him in position to end his and McLaren's lengthy win droughts, on a memorable afternoon in Monza
For the second time in 2021, McLaren will line up for the start of a grand prix from the first row. It knows it has the chance of "glory" if things go well for Daniel Ricciardo and Lando Norris at the start of the 2021 Italian Grand Prix, but even if they just maintain their grid positions, signs from the rest of the Monza weekend suggest success is very possible for Formula 1's other orange army
OPINION: The Formula 1 cost cap has been billed as a saviour to several teams and helped to guarantee their viability for investors. But there already exists another mechanism that effectively had the same purpose, and serves as a strong deterrent for those with the means to go it alone in setting up a new team