Ahead of today's opening session, the air temperature is 30 degrees C, while the track temperature is 50 degrees. It is bright, sunny and hot. Indeed, there is already a heat hazard warning in place for Sunday.

In terms of upgrades, almost all of which are circuit specific, McLaren has a new Rear Wing and Floor Furniture. The high isochronal rear wing has been modified to deploy the flap to an alternative position in straight line mode in combination with a less loaded beam wing, resulting in a larger reduction in drag. In other words, the so called H-Wing, McLaren's version of the Macarena. A small modification to the floor furniture, will result in better flow conditioning and resultant improvement of aerodynamic performance of the floor as well as drag reduction.

Mercedes has a new Rear Wing and Front Bodywork. Removing the rear wing winglets reduces assembly camber shedding local downforce and drag at a ratio appropriate for Monza low downforce (L/D), while the mirror stay trim reduces local camber and loading, shedding local downforce and drag at a ratio appropriate for Monza.

Red Bull has a new Rear Corner, Floor Body, Exhaust Tailpipe and Front Wing. To improve reliability of the rear wheel bodywork assembly, the gaitor providing an aerodynamic seal has been changed to reduce the probability of splitting from the wishbone and now removed winglet junctions. Meanwhile, in seeking to validate an alternative geometry, the edge profile has been revised for evaluation in Monza. The new geometry will revise the flow to create more local load with improved aerodynamic stability. In order to operate the power unit reliably around the Monza circuit with its unique demands, the tailpipe bracket has been trimmed to offer less blockage. Finally, a trimmed front wing end plate dive-plane is available for evaluation in Monza which aims to improve downstream load from the floor.

Ferrari has a new Floor Board, Mirror Stay, Rear Corner and RV Tail. Seen as a package, the primary aim of these modifications has been to adapt to Monza's peculiar characteristics and car aerodynamic efficiency requirements. All the steps have been targeting aerodynamic drag saving, coming along with downforce reduction as a natural consequence, but in a favourable ratio for this track.

Williams has a new Halo, Front Wing and Floor Body. The Grove outfit has modified the local pressure distribution around the driver cockpit area. This results in a downstream flow field change which benefits efficiency levels specific to Monza. The rearward element on the front wing assembly has been modified to suit the balance requirement of the circuit. Finally, a local trim has been applied to the floor board geometry. This is a further circuit specific change, altering the balance between downforce and drag at the front of the main floor.

Racing Bulls have a new Rear Wing and Exhaust Tailpipe. The rear wing changes facilitate increased flap travel in Straight Mode. This allows an efficient drag reduction which suits the nature of the circuit. The tailpipe updates improve the flow management around the centreline of the car, allowing the floor and rear wing to perform more efficiently.

Aston Martin has a new Front Suspension and Floor Edge. The external fairing for one of the front suspension members has been modified to improve alignment with the onset flow, while the geometry in front of the rear tyre has been modified to improve the airflow to the underside of the floor increasing load generated in this area.

Haas has a new Floor, Bodywork and Rear Corner. The floor update focuses on optimising the main expansion region and associated side geometry to improve airflow behaviour throughout the floor. The revised design increases floor efficiency, delivering a net gain in overall aerodynamic performance and downforce production. The revised bodywork has been developed in conjunction with the new floor design to maximise the aerodynamic benefit of the floor package. The updated geometry improves airflow management around the car while providing the necessary cooling performance for all operating conditions. The aerodynamic changes introduced by the new floor and bodywork package alter the flow structures reaching the rear corner region. To accommodate these changes and maximise the benefit of the update, the rear corner fairings have been re-optimised and the rear drum deflectors realigned, improving local flow management and overall aerodynamic efficiency.

Alpine has a new Front Wing Endplate and Rear Wing. As part of the French team's front wing development program, the vane has been redesigned to increase the local load and improve local flowfield, while the SM pod on the launch rear wing has been adjusted to better suit the low drag nature of the Monza track.

Cadillac has a new Forward Floor and Diffuser Vane. The revised forward floor board stay geometry improves flow conditioning to the rear of the car, increases structural stability of the component and improves overall aerodynamic load at the rear of the car, while a small vertical turning vane has been added to the inner trailing edge of the outboard diffuser sidewall, which improves aerodynamic performance in the outer floor channels and increases the load at the rear of the car.

Audi is the only team that hasn't brought any upgrades or updates.

There are four reserve drivers on duty this morning, Ayumu Iwasa at Red Bull, Colton Herta at Cadillac, Luke Browning at Williams and Paul Aron at Alpine.

Green light and Iwasa leads the way, followed by Herta, Ocon, Alonso and Bearman.

As more drivers emerge, hard and medium is the order of the day.

The Ferrari pair emerge, the crowd rising to applaud them.

Many of the cars are sporting aero rakes, as the teams make full use of the wind-tunnel like nature of the straights here.

Iwasa sets a benchmark 34.202, but Ocon soon responds with a 30.541.

Russell goes top with a 25.258, ahead of Tsunoda, Lawson, Colapinto, Hamitln and Leclerc.

Lawson, on softs, improves to second with a 25.785, as Lindblad goes third.

"What is he doing?" asks Iwasa of Aron.

A 25.637 puts Antonelli second, 0.378s off his teammate's pace. However, moments later he is demoted by Piastri (25.333).

Quickest in the final two sectors, Leclerc (hard) goes top with a 24.482, however Lawson responds with a 24.383.

Norris (medium) goes third with a 24.526.

"Lots of oversteer, especially in Turn 7," warns Sainz, as Antonelli goes third with a 24.515.

Piastri improves to second with a 24.394.

It has just been announced that the FIA's International Court of Appeal has imposed the two 5s penalties given to Pierre Gasly in Monaco, thereby stripping the Frenchman of third place and promoting Isack Hadjar and Oscar Piastri.

Russell retakes the top spot with 23.802, however a 23.719 sees Norris demote the Mercedes driver.

Herta has stopped between the two Lesmos, as Hamilton goes third with a 23.891.

The VSC is deployed as Herta's Cadillac is removed from the side of the track.

The marshals' job isn't helped by the fact that the car appears to be in gear. Consequently, the session is red-flagged.

The session resumes with 33 minutes remaining and Antonelli leads the way, followed by his teammate, Alonso, Ocon and Hulkenberg, most having made the switch to softs.

No sooner has Antonelli posted a 23.644 then his teammate responds with a 23.312, despite a poor opening session.

Lawson goes third with a 23.712, but is demoted when Leclerc, on mediums, goes top with a 23.008, the Monegasque quickest in the opening and third sectors.

The cameras cut to an understandably disappointed looking Gasly in the Alpine garage, along with Flavio Briatore.

Norris improves to fifth with a 23.719, ahead of Lindblad, Hamilton and Colapinto.

"That's so bad," declares Iwasa as he encounters a number of much slower cars that appear to be weaving.

Hamilton, like his teammate, on mediums, improves to third with a 23.561.

The Aston Martin pair appear to be sticking to their own programme, both currently over 3s off the pace.

All at once Antonelli, Norris and Sainz miss the first chicane.

"What is he doing, man" asks Tsunoda of some spectacularly bad driving from Aron, who is not only weaving but impede the RB driver heading into the first Lesmo.

An incident involving Colapinto and Bearman has been noted as Browning is the latest to miss the first chicane.

The Mercedes pair have switched back to the mediums.

Quickest in S3, Hamilton goes second with as 23.181, 0.173s down on his teammate.

Early days, but that new power unit appears to be making a difference.

Alonso heads out on mediums, the Spaniard currently 21st, 3.135s off the pace.

Attention switches to Sunday, as Alonso has a hairy moment in the first Lesmo, despite which he improves to 18th with a 25.780.

Bearman misses the first chicane, while Sainz takes the long way around.

Drivers are warned of gravel on the track at the first and second chicanes.

According to Cadillac, Herta suffered a hydraulics issue.

Hamilton misses the second chicane.

A late improvement sees Aron go tenth with a 24.177.

The session ends. Leclerc is quickest, ahead of Hamilton, Russell, Lawson, Antonelli, Norris, Lindblad, Bortoleto, Colapinto and Aron.

Piastri is eleventh, ahead of Tsunoda, Hulkenberg, Bearman, Browning, Sainz, Iwasa, Ocon, Bottas, Stroll, Alonso and Herta.

Impressive pace from Ferrari, especially on the mediums. However, Russell is right up there, though Antonelli is focussed on race set-up as opposed to qualifying due to his grid penalty.

The Red Bull is also looking strong, while Norris cannot be written off at this early stage.