Williams' George Russell was the first car out on the sunny streets of the principality, which traditionally open on Thursday for F1 practice.
Sainz was first to set a reasonable laptime of 1m16.241s mediums in the Ferrari.
World champion Lewis Hamilton quickly bested Sainz's time in the Mercedes with a 1m15.858s, before Sainz struck back with a 1m14.457s aboard the SF-21.
Sainz's Ferrari ...Keep reading
Sainz was first to set a reasonable laptime of 1m16.241s mediums in the Ferrari.
World champion Lewis Hamilton quickly bested Sainz's time in the Mercedes with a 1m15.858s, before Sainz struck back with a 1m14.457s aboard the SF-21.
Sainz's Ferrari ...Keep reading