Verstappen spent both sessions complaining over the radio about the behaviour of his car.
In the first session, the three-time champion was lacking grip at the Acque Minerale combination of corners, while in the afternoon he said: “It is difficult everything, man. This time suddenly the front grips up a lot and I almost spin.”
Verstappen ended up 0.541secs slower than Leclerc and said: “Difficult day. Difficult to get a good balance and just not feeling comfortable in the car, moving around a lot, very easy to lose it.
“Also the long run was really bad. So definitely a few things we have to improve if we want to be competitive tomorrow. From our side, just a bad day.”
Leclerc, by contrast, looked comfortable in the upgraded Ferrari all day, after the team introduced their first major development to the car, featuring revised aerodynamics around the bodywork and floor.
He said: “For now, everything went quite smoothly. The feeling with the car is good, the upgrades are working as expected and it has been a very smooth day.
“It is great being at home. It is always a special feeling being Ferrari here. It would be great if the weekend continued in that direction but on Saturday the conditions will change massively.
“The wind direction will completely turn around, which will have a big effect on all the cars and we will have to be the best at anticipating those changes.
“Track position is absolutely everything here so qualifying will be super-important and it will be important for us to do the job in qualifying.”
Norris, driving the same upgraded McLaren with which he won in Miami, also looked competitive – he retained the fastest time in the second sector throughout the session, underlining his inherent pace despite his lowly position in the timesheets.
He said: “Pretty reasonable day. Little bit of a messy P1. Not the cleanest day but we made a really good step from P1 to P2 and it felt really good out there. I think we’re in a good position. Positive day and a good start to the weekend.”
On the race-simulation runs later in the session, Piastri was very slightly fastest, from Leclerc, Norris and Hamilton.
Verstappen was still struggling, despite Red Bull bringing their own upgrade, unable to set consistently quick times and running wide at Rivazza at one point.
Tsunoda’s one-lap pace was not mirrored in the long runs, suggesting RB might have been running light on fuel or with their engine turned up more than other teams for the qualifying simulations.
The Mercedes drivers were both pleased by the effect of the upgrades Mercedes had introduced, but Russell said he thought McLaren looked the quickest team.
Russell said: “The car’s feeling great today and Lewis and I both had a really good feeling behind the wheel. We look reasonably competitive. Slightly closer than in Miami.
“McLaren still look the favourites and are probably the quickest again.”