Lewis Hamilton was ranked fifth in the first session on Italy's first match at Ferrari and fifth in the fifth, behind Piastri and 11th in the second Ferrari.
The seven-time champion said he was happy with the car early on, but between meetings, he “changed two things that shouldn’t have any impact at all, and it was the smallest change we could have probably made this year, and we had some brake issues that made it a huge difference, so that was a struggle.”
Hamilton is vague about this question.
Asked if it was related to changes he was used to with another brake manufacturer in Mercedes, he said: "It's not a transition. It's a performance of …" and then his voice fell behind.
In the pool interview, the only driver visit provided to the media on Friday, he was not forced to explain.
He added: "It's a lottery. We're going to roll the dice. We put on a dice and it works fine, plus one, it won't, we'll see. I hope we figure out something out tomorrow. We'll definitely work on it."
Russell, who has strong qualifying matches this season, said the decision to bring the three softest tire compounds into this game could have an impact.
Pirelli has expanded its range to six compounds this season, introducing the softest tires, initially only used in street circuits, where tire degradation is usually low.
However, it has been decided to use it in Imola to try to add an extra size to the Grand Prix, hoping that the softer compound range can shift the race from the standard one-stop strategy on the track.
"There are a lot of tire degradation. The first time we've had the softest tires here this season, which makes things a little flavorful.
“But we know that McLaren usually seems to expand their advantages under these conditions.
"I saw the Oscars and I didn't. He passed Max and went. That's where we were in the team for a moment. We knew we were fighting with Max and Ferrari."
Williams driver Alex Albon said he didn't expect the strategy to change, saying the mid-sized tires have proven to be "very good" and "quite low-level".
The racing race was interrupted when the Racing Bulls were ranked seventh overall, after Tamburello Chicane exited and fell into a hurdle.
The car seems to have escaped to a large extent, but Hadjar tries to return to the track and the race meeting is marked red, Hadjar is trapped in gravel.
It did restart, but it could only allow some pilots to make a flight lap in time.
In Hadjar's fastest time list, Yuki Tsunoda ranked eighth in the second Red Bull, ahead of Albon and teammate Carlos Sainz.
Lance Stroll has the responsibility to test Aston Martin's major upgrades, which include a new floor, fell at No. 17.
Teammate Fernando Alonso, who made a back-to-back comparison in previous cars, had three positions higher and took 0.121 seconds faster.
Stroll said the car felt "the same". Although it has new floors and engine covers, Canadians describe the upgrade as a "small change."
The first practice was over prematurely when Sauber's Gabriel Bortoleto crashed into the corner of the second Rivazza, flashing to the obstacles almost the front line and destroying his front wing and nose.