Ferrari moved into a favourable position at Monza after Charles Leclerc posted the fastest time in first practice, putting the team in a position to exploit Kimi Antonelli's impending grid penalty. Leclerc was 0.173 seconds quicker than Lewis Hamilton, with George Russell third on the timesheets.
Liam Lawson, standing in at Red Bull for the injured Isack Hadjar, finished fourth, ahead of championship leader Antonelli, who was 0.636 seconds adrift of Leclerc. Antonelli leads Hamilton and Russell by 59 points in the drivers' championship but faces a weekend setback, he will start at the back of the field on Sunday after receiving a penalty for installing a new power unit.
The opening hour was staged in sweltering conditions and was shortened by a red flag when rookie Colton Herta, substituting for regular Cadillac driver Sergio Perez, stopped on track with a hydraulic issue. The interruption reduced on-track running and left teams with less time to refine qualifying trim.
Lando Norris ended the session sixth for McLaren. The world champion, who has won the last two races in Hungary and Zandvoort, ran off at the Turn One chicane, following Antonelli and the Williams of Carlos Sainz across the gravel. Russell and Leclerc also pushed the circuit limits during the session, while teams flagged traffic problems over the radio.
Arvid Lindblad was seventh for Racing Bulls. Audi's Gabriel Bortoleto, Alpine's Franco Colapinto and rookie Paul Aron, who replaced Colapinto's team-mate Pierre Gasly for the first hour, rounded out the top 10. Oscar Piastri was 11th for the other McLaren, more than four tenths slower than his team-mate. Yuki Tsunoda, on a second consecutive weekend at Racing Bulls in place of Lawson, was 12th, with Nico Hulkenberg 13th and Oliver Bearman 14th.
The session also coincided with an off-track development: McLaren and Red Bull won appeals against the result of the Monaco Grand Prix after controversy over multiple incorrect pit-lane speeding penalties. That decision strips Alpine's Pierre Gasly of the podium he briefly held following a separate appeal that had overturned two five-second penalties.
Ferrari leaves the first session with clear one-lap pace and the chance to convert that into stronger starting positions, while rivals must weigh how to respond as the weekend progresses with qualifying and race running still to come.
