Ahead of today's opening practice session the air temperature is 23 degrees C, while the track temperature is 39 degrees. It is bright, sunny and warm.

There are five reserve/third drivers on duty this morning, Leonardo Fornaroli at McLaren, Frederik Vesti at Mercedes, Ryo Hirakawa at Haas, Paul Aron at Alpine and Colton Herta at Cadillac.

In terms of updates, McLaren has a new Rear Wing, Floor Body, Front Corner, Front Corner and Rear Corner. The rear wing features a small revision to the endplate resulting in improved flow conditioning and aerodynamic characteristics across the full operating range. The new floor and board features a modified base shape and furniture, resulting in an improvement in flow conditioning and local load generated across all conditions, while a small modification to the front corner furniture results in an improvement in flow conditioning around the front tyre and resultant aerodynamic performance. To meet the increased brake cooling demands of this circuit, a larger front brake cooling exit has been designed aiming at minimising the detrimental impact on aerodynamic performance, while an update to the rear corner furniture, featuring a revised winglet arrangement is aimed at an efficient increase of aerodynamic load.

Mercedes has a new Rear Wing, Coke/Engine Cover and Tail. The new winglet on the front wing increases local wing chord and camber increasing local downforce and drag at a ratio appropriate for Budapest. The engine cover's increased exit size is to achieve adequate mass flow through the sidepods to ensure we have adequate cooling for this track, while running the tail winglet into the rear wing brace increases local downforce and drag at a ratio appropriate for this track.

Red Bull has a new Rear Wing, Floor and Rear Wing. By exploiting the permitted rear wing pylon geometry, the camber of the pylons has been increased to extract a little more load and maintain, even enhance the flow stability. Having observed some competitor designs, the floor diffuser geometry has gained surface area adjacent to the rear impact structure offering a local gain in load, while following iterations of the rear wing design, a revised flap pairing has become available for the this weekend offering more load from revised camber and chord geometries. This change is accompanied by a minor revision to the lower brace (wing) geometry as part of the new design.

Ferrari has a new Rear Wing and Rear Wing Endplate. Part of the standard development cycle, this further iteration of rear wing has been focused on increasing load in a robust way. The additional winglet cascade is meant to increase rear downforce at the expense of aerodynamic efficiency, and is optional.

Williams has new Rear Wing and Floor Body. To suit the demands of the Hungaroring, the Grove outfit has introduced an optional rear wing flap geometry which offers an increase in downforce across the rear of the car. The floor body is a further circuit specific change, which modifies the aerodynamic loading on the outboard floor body and surrounding components at the rear corner of the car.

Racing Bulls have a new Roll Hoop, Rear Wing and Cooling Louvres. The roll hoop introduced at Spa creates additional freedom in that area. The winglets improve the quality of the airflow reaching the rear of the car. A combination of changes to the SM pod and to the flaps & auxiliary components allows additional load to be generated by the rear wing, which is well suited to the circuit characteristics, while opening the louvres on the bodywork allows more airflow through the radiators, increasing engine cooling and thus increasing the range of operating conditions.

As for Aston Martin... there's a new Front Wing, Front Wing Endplate, Nose, Front Corner, Floor Body, Floor Fences, Floor Edge, Diffuser, Sidepod Inlet, Coke/Engine Cover, Cooling Louvres, Rear Suspension, Rear Corner, Rear Wing, Beam Wing and Rear Wing Endplate. The front wing, endplate and nose are a package to improve the performance of the front end of the car in combination with the other car updates, while the new front brake duct external elements work alongside the new front wing to manage flow around the front wheels. All floor changes are developed as a package to increase the load on the floor and therefore improve the car performance. The bodywork package has evolved to improve the feed to the rear of the car and complement the changes to the floor geometry, while the louvres provide the usual range of options to allow the setup of the cooling system for optimum performance depending on conditions. The rear suspension and rear brake ducts modifications were developed with each other and the changes to the rear of the floor, while the three components of the rear wing increase CM load while reducing SM drag, and are aligned with other changes to the rear of the car.

Haas has a new Rear Wing. The revised SM Fairing increases local aerodynamic loading and, in combination with a more aggressive Gurney flap configuration, contributes to increased rear wing downforce.

As does Audi, where a new endplate profile is introduced. The update is intended to deliver a local aerodynamic load increase while contributing to the overall aerodynamic efficiency of the race car.

Cadillac has a new Front Corner whereby the front brake duct surfaces have been updated to increase both the inlet and exit flow areas, improving airflow through the ducts and providing additional brake cooling capacity.

Green light, and Hirakawa is first out, followed by Ocon, Hadjar, Hulkenberg and Herta.

As more drivers head out it is mostly mediums but a few drivers are on hards.

Of the first wave, Leclerc goes quickest with a 22.705, while Aron goes second and Alonso third!

Russell posts a 22.056 as Stroll goes fourth.

"Unbelievable these guys," says Verstappen of a slow Sainz on the racing line, "that was really dangerous."

Leclerc retakes the top spot with a 20.884 as Sainz claims he had no radio.

Hamilton does well to control a nasty snap coming out of the final corner.

A 20.798 sees Russel go top, ahead of Leclerc and Russell.

Fornaroli goes fourth with a 22.084, ahead of Norris and Lindblad.

Sainz has been noted for driving erratically, as Verstappen complains about his downshifts, not for the first time this season.

Leclerc is held up by his teammate in Turn 12, said teammate having just gone third with a 21.065.

Leclerc goes on to raise the bar with a 20.287, as Verstappen is noted for driving erratically in that he essentially brake-tested Sainz, who is to be investigated after the session, as is the Dutchman.

Hamilton goes second but remains 0.326s off his teammate's pace, as Lawson goes fifth, ahead of Hulkenberg, Lindblad and Norris.

"This car feels really bad, too stiff," reports Hamilton. Asked if it is at the front or rear, he replies: "Overall".

Bortoleto improves to fifth with a 41.425.

McLaren is running its version of the Macarena wing, albeit only on Fornaroli's car.

Norris, Ocon and Hirakawa are the first to switch to the softs, with 33 minutes remaining. Verstappen and Russell follow suit.

Russell improves to 20.066 on the red-banded rubber, as Norris aborts after running wide in Turn 11 and pits.

A 19.559 sees Verstappen go top as Aron has a mighty wobble exiting the final corner.

"The rear wing is working well," reports Fornaroli.

Quickest in all three sectors, Leclerc crosses the line at 19.075, eclipsing Verstappen by 0.484, as Hadjar goes third (19.997).

A big, big lock-up for Russell as Hamilton improves to third with a 19.618.

Perez goes fourteenth as Stroll stops at Turn 3, with what appears to be a left-rear suspension failure.

The session is red-flagged.

Replay shows the rear suddenly snapping out as he exited Turn 2. Hard to say what happened, possibly a loose wheel. Adrian Newey looks suitably concerned.

"Somethings wrong with the downshifts and upshifts," reports Hamilton.

The session resumes with 17 minutes remaining, and Ocon is first out. He is followed by Gasly, Herta, Hirakawa, Sainz and Vesti.

Looking to improve on 22nd (who wouldn't?), Sainz loses a heap of time behind Aron.

Alonso (21.550) improves to twelfth as Vesti (20.467) goes seventh.

Aston Martin reports a suspected "rear left suspension issue".

A massive four-wheel lock-up for Sainz in Turn 1, the Spaniard doing well to keep his Williams out of the barriers.

Since the red-flag attention has turned to Sunday.

"Uh, something has broken," says Leclerc as he coasts into the pitlane and subsequently stops. His crew rush to rescue him.

Sainz appears to be under investigation for driving erratically again.

As the session ends Sainz is shown the black and white flag for impeding.

So, Leclerc is quickest, ahead of Verstappen, Hamilton, Hadjar, Russell, Bortoleto, Vesti, Hulkenberg, Lindblad and Lawson.

Norris is eleventh, ahead of Ocon, Alonso, Gasly, Albon, Fornaroli, Hirakawa, Perez, Aron, Herta, Stroll and Sainz.

Early days, but other than that superb lap from Leclerc, the other driver who must be feeling good is Alonso who is thirteenth quickest, 2.4s off the pace but on the hards.