McLaren's Lando Norris was headed by Charles Leclerc in Friday's practice.
The fastest man was Leclerc, who was 0.217 seconds quicker than the second fastest man.
The two drivers who will most likely be Leclerc's main competitors this weekend were not in sight.
Sainz and Verstappen were 0.231 and 0.283 seconds off the pace, respectively.
The car seemed to be struggling.
Russell said that the brakes would lock going into the first corner.
He asked what was happening at Turn One. Without locking brakes, I can't get around it.
In 11th place and 1.102 seconds behind Leclerc, Lewis Hamilton said his car was "unstable" on his race simulation run.
Leclerc had to abandon his race-simulation run when he felt a problem with the engine at the beginning of it.
He asked if there was a problem. His engineer was checking it.
He was able to get out on track again, and he had a significant advantage over both Verstappen and Leclerc with both running the medium tire. Sainz's first run was on the softs.
Russell was lagging behind Verstappen on average on the race run as Mercedes were in poor shape.
Leclerc lost a lot of ground in the championship when he crashed in France.
Verstappen leads the race by 63 points.
The two most intriguing upgrades were at the two companies.
A form of end-plate has been reintroduced by the company. These parts of the rear wing were replaced with a curved transition from the sides of the wing to the down force-creating elements in order to prevent them from being used.
The package of changes made it easier for cars to follow each other.