Ahead of today's opening session the air temperature is 27 degrees C, while the track temperature is 40 degrees. It is bright, with clear blue Texas skies.

As Cadillac meets its official requirements, Colton Herta is at the wheel of Sergio Perez' car, while there are more 'exclusive' liveries than you can shake a stick at.

In terms of updates, McLaren has a new Front Corner, Rear Corner and Diffuser. The front corner scoop and furniture have been revised in conjunction with the front suspension fairings aiming at improved flow conditions, while the rear corner furniture has been revised to achieve an improvement in flow conditioning as well as increased local load. The diffuser geometry has been modified aiming at an improvement of flow conditioning and local load across the speed range.

Red Bull has a new Front Wing and Front Corner. Taking the recently introduced front wing geometry, an option to operate with the tyre temperature turning vane has been added for evaluation, offering a tyre surface temperature measurement as well as more local load with similar flow stability. At the rear, the periphery of the gaitor has been revised to reduce the likelihood of tearing the elastomeric material during running by reducing the strain in the regions of highest deflection when steering lock is applied.

Ferrari has a new Floor Body, Floor Board, Sidepod Inlet/Coke Sidepod and Diffuser. Key development features have focused on increasing floor downforce (on both front and rear parts) whilst also increasing energy levels and flow stability sent towards the back of the car. Benefitting from improved onset flow quality, the diffuser expansion and overall geometry has been further optimized, and returns increased aerodynamic load in an efficient way.

RB has a new Front Wing, Rear Wing, Floor Body and Coke/Engine Cover. The front wing endplate plays an important role in managing the flow around the front tyres. These updates further improve the management of the flow field downstream. Meanwhile, the camber and chord of the rear wing flap elements has been modified to clean up the local flow and allow the wing to generate more load. A combination of developments across a number of key floor components will improve the overall flow management around the floor. This translates into an efficient downforce increase. Working in combination with the updates made to the floor, the changes to the engine cover help manage the flow as it passes around the side of the car and towards the rear.

Audi has a new Front Corner, Front Floor and Mirror stay. The revised front brake duct provides updated cooling characteristics together with associated aerodynamic performance, complementing the latest development steps introduced, while the updated floorboard geometry is intended to improve local flow conditioning and support the overall aerodynamic performance of the floor assembly. Finally, the updated mirror stay geometry complements the revised front corner configuration and supports the overall aerodynamic performance of the car package introduced lately.

Alpine has a new Floor Corner and Rear Wing. The rear floor corner has been redesigned to improve the local flowfield interaction with the rear corner while also increasing local load, while the second and third element flap of the rear wing have been redesigned to improve rear wing flow quality and overall load delivery.

For its home race, Cadillac has new Floor Fences and Cooling Louvres. Th revised geometry of the floor fences improves flow conditioning to the rear of the car and reduces sensitivity to changes in car attitude, whilst retaining overall aerodynamic load. Meanwhile, the sidepod top deck louvres have been updated to increase the power unit cooling capacity, whilst minimising the effect on aerodynamic performance.

Green light and Colapinto leads the way, followed by Bortoleto, Herta, Sainz and Albon.

As more drivers head in it's a mixture of hards and mediums.

Of the first wave, Leclerc (medium) goes top, ahead of Russell, Verstappen and Lawson, however, Norris (medium) responds with a 38.715.

As ever, Verstappen is not happy, he heels there is something wrong with his steering.

Despite his issue, Verstappen goes top with a 38.040 on the hards, until Leclerc responds with a 37.430.

Piastri goes third, ahead of Lawson, Norris and Stroll.

A number of drivers, most notably Bottas, are running aero rakes.

Quickest in S2, Hamilton (mediums) posts a 37.235.

Down in 18th, Colapinto has switched to the softs, as Antonelli goes sixth with a 38.252 on the hards. Teammate Russell is currently seventh.

Leclerc raises the bar with a 36.761, and though quickest in the opening two sectors, a poor final sector mans Norris can only manage 37.467.

Hamilton consolidates his second place with a 36.835, as Bearman improves to twelfth.

"Check the front wing, something has happened," reports Russell as Alonso goes eleventh.

Piastri improve to fourth, as Lindblad goes thirteenth. The RB driver will incur a grid penalty after taking on a new ICE. Likewise Bortoleto who has taken on an additional Energy Store.

With 35 minutes remaining, Colapinto, Herta and Albon have yet to post times, though all three have been out. That said, Colapinto is in the alpine garage and appears to have an issue.

Switching to the red-banded rubber, Hulkenberg improves to eighth with a 37.957, as Lindblad and Herta also switch to the softest rubber provided here.

Hadjar is the first of the big guns to fit the softs, as Hamilton and Russell follow suit.

Hulkenberg reports "very weird" behaviour from his power unit coming out of the final corner.

Hadjar improves to third (36.918) on the softs, while Russell posts a 36.889.

Leclerc posts a 36.052 on the red-banded rubber, while his teammate has opted for two warm-up laps.

Verstappen (softs) goes second with a 36.136, as Bearman and Hadjar become the latest drivers to have times deleted for exceeding track limits, Turn 20 seemingly the most problematic corner.

Antonelli goes fourth Bearman ninth and Gasly eleventh.

Verstappen goes top with a 35.860, the Dutchman quickest in S1 but losing pace as the lap progressed.

Antonelli goes quickest in S2 but remains fifth, 0.481s off the pace.

With 15 minutes remaining, as attention switches to Sunday, it's: Leclerc, Verstappen, Norris, Russell, Antonelli, Hamilton, Piastri, Bortoleto, Lindblad and Lawson.

Still no times for either Williams driver, despite 23 laps between them, but hey, let's look forward to next year's celebrations.

Alonso improves to twelfth with a 37.688.

"Wasn't I meant to go with hards," asks Antonelli, his team apologising for the error.

"Basically on the two cars, we've got separate things," confirms Audi boss, Alan McNish. "On Gabi's car, we've got the latest of the upgrades on it and on Nico's car, he is on the standard set-up that we had in Singapore.

"From that, we're just doing the back-to-back correlation points as normal and then both cars will switch... certainly Nico's car will switch to the full package."

Finally, Albon goes 20th with a 39.375 however his time is deleted for a violation at Turn 19. The car looks a real handful. Sainz goes 19th with a 38.846.

Leclerc has switched to the mediums and Russell to the hards, as the rest of the big guns stick with the softs.

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

Bearman is eleventh, ahead of Alonso, Stroll, Hadjar, Gasly, Ocon, Colapinto, Hulkenberg, Sainz, Bottas, Herta and Albon.