Russell’s benchmark of 1m32.741s left him just 0.026s clear of Antonelli at the end of the session, with Lando Norris best of the rest in third for McLaren, narrowly ahead of teammate Oscar Piastri.

Mercedes established itself at the front once the session evolved into soft-tyre running, with Russell repeatedly trading fastest laps with Antonelli before edging clear in the closing stages.

Antonelli had briefly gone quickest with a 1m31.692s earlier in the hour, only for Russell to respond soon after.

Behind them, McLaren emerged as the nearest challenger, though both Norris and Piastri remained around two tenths adrift of the leading pace.

Ferrari slotted in behind, led by Charles Leclerc in fifth, while Lewis Hamilton ended the session sixth after improving on soft tyres.

Cool but sunny conditions greeted teams at the start of the session, with a 17°C ambient temperature making tyre warm-up difficult, particularly for those running the hard compound early.

Initial laps were largely exploratory, with several drivers completing short runs before returning to the pits.

Early times were traded between Piastri and Russell, with the Australian briefly fastest before Russell went quicker despite running the harder compound.

Leclerc also featured near the top in the opening phase, edging ahead of Russell by just 0.013s during the first round of runs.

Track action quickly intensified as the session progressed, with traffic becoming a recurring issue.

Norris ran wide at Spoon, while Antonelli locked up at the hairpin on one of his early laps. Russell also had a moment of his own, running wide at Spoon after reporting a brake snatch.

There was a close call at Turn 1 involving Leclerc and Piastri as they ran three-wide with an Alpine, with the Ferrari emerging ahead. Piastri later reflected on the moment over team radio, saying: “Well, that didn’t go well.”

Further incidents followed as drivers pushed harder on lower fuel. Alex Albon ran through the gravel at Degner 2 and brushed the barrier, while later contact between Albon and Sergio Perez at the Casio Triangle left debris scattered across the circuit. The clash is set to be investigated after the session.

Traffic continued to cause frustration, with Liam Lawson voicing his displeasure after encountering a slow Carlos Sainz, while also being involved in a separate on-track moment with Franco Colapinto as drivers backed off to create space.

Elsewhere, teams worked through varied programs, with some focusing on longer runs and others switching between compounds.

Aston Martin endured another low-key session, with Lance Stroll and stand-in Jak Crawford completing limited mileage, the latter restricted to just 11 laps.

By the final stages, the field had spread significantly, with more than five seconds covering Russell and Stroll at the foot of the order, underlining the differing approaches across the grid.

Max Verstappen had a low-key session, finishing seventh, one spot ahead of Lawson. Esteban Ocon and Arvid Lindblad rounded out the top 10, while Gabriel Bortoleto and Nico Hulkenberg followed for Audi.

Isack Hadjar, who reported early balance issues with his car pulling under braking, finished 13th ahead of Oliver Bearman and Pierre Gasly.

Franco Colapinto placed 16th, with Carlos Sainz and Albon further back after their disrupted sessions. Perez ended the hour 19th for Cadillac, ahead of teammate Valtteri Bottas, with the Aston Martin pair completing the order.

Despite the incidents and interruptions, teams were able to complete the bulk of their programs, with Mercedes emerging as the early benchmark heading into the remainder of the Suzuka weekend.

Second practice for the Japanese Grand Prix gets underway at 3pm local time (5pm AEDT).

Results: Formula 1 Japanese Grand Prix, Free Practice 1