IMOLA, Italy -- Max Verstappen said Red Bull has work to do to maintain its big advantage over the rest of the field after a tough day of practice ahead of the Emilia-Romagna Grand Prix.
Verstappen looked out of sorts with his Red Bull, which has upgrades ahead of this weekend's race.
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The runaway championship leader ran wide twice in the first practice session and again in the second session on Friday afternoon.
Ferrari's Charles Leclerc went quickest in both sessions at the circuit a short way away from the team's headquarters at Maranello.
Miami Grand Prix winner Lando Norris and McLaren teammate Oscar Piastri both have the team's upgrade on the car this weekend, and the team had a solid start to the weekend.
Reflecting on how qualifying might look on Saturday, Verstappen said: "I guess it can't be worse than what we had today, right?
"We'll look at a few things that we can do better for tomorrow. But yeah, it looks a bit like the others took a bit of a step forward. And from our side just a bad day.''
Verstappen said the day was a constant struggle to get on top of the car.
"A difficult day. Just difficult to get a good balance and just not really feeling comfortable in the car, moving around a lot," Verstappen said.
"It's very easy to lose the car, so we have a few things that we have to look at because today definitely ... just bad, just not comfortable.
"Also the long run was really bad, so definitely a few things that we have to improve if we want to be competitive tomorrow.
"Today we were just severely off the pace that we need to fix."