Charles Leclerc of Ferrari topped the first practice for the team's home Formula One Emilia Romagna Grand Prix in Italy on Friday, while champion Max Verstappen of Red Bull struggled throughout the session.
Leclerc clocked 1 minute 16.990 seconds around the Autodromo Internazionale Enzo e Dino. He was followed by the Mercedes of George Russell, who was 0.104s behind, and team-mate Carlos Sainz.
Verstappen was only fifth, behind Sergio Perez in the second Red Bull, struggling in the middle sector and going off the track a few times.
The session was suspended for a few minutes after Alex Albon stopped his Williams at the exit of the Acque Minerali with an apparent technical issue.
Ferrari and Mercedes are among the teams that brought upgrades to Imola, but Red Bull also have new parts as they try to bounce back from a defeat at the Miami Grand Prix two weeks ago.
The champions claimed victory in all but one of the 22 races held in 2023, but they've already been beaten twice in six events this year thanks to efforts from Sainz in Australia and McLaren's Lando Norris in Miami.
In Australia, however, Verstappen didn't complete the race due to an issue in his car.
Second practice session is later on Friday, with the last practice and qualifying on Saturday ahead of Sunday's race.
Imola last hosted a race two years ago. Last season's event was cancelled after horrific flooding hit the Emilia-Romagna region, where the circuit is located.
