Ahead of today's second practice session, the air temperature is 24 degrees C, while the track temperature is 36 degrees. It remains bright and sunny but very windy.

As a reminder, this weekend's upgrades are...

Mercedes: front wing flaps, mirrors and rear wing flap
Red Bull: front brake cooling, floor stay and floor edge
Ferrari: rear wing and mirrors
McLaren: rear wing, bodywork (cooling) and front wing flaps
Alpine: sidepod inlets, rear wing flap, beam wing and front wing flap
Alpha Tauri: front wing flaps and beam wing
Alfa Romeo: front wing flaps and rear wing

Most teams have trimmed their front and rear wings, while Red Bull has added an external wire to support the floor plus modifications to the floor for more downforce. Ferrari have their Miami rear wing, which they did not actually use there.

Sergio Perez was quickest this morning, edging out Leclerc, Verstappen and Sainz in a session that was noticeable for the return of porpoising, with Mercedes and Ferrari the most visibly affected, though Red Bull was also suffering. Indeed, the Austrian outfit's cause was not helped by a wildly oscillating DRS flap on Verstappen's car.

It was an early bath for Schumacher and Latifi who both suffered technical issues, whilst Ricciardo was technically last on the timesheets.

The lights go green and Sainz is already waiting at the pitlane exit, as he heads out he is followed by Ocon, Vettel, Norris and Hamilton.

As more drivers head out, most are on mediums, the exception being the McLaren pair who sport hards.

Latifi and Schumacher are among the early risers.

Norris heads off down the escape road at Turn 3 following a significant lock-up, the Briton having great difficulty getting his car back on track again.

The early benchmark is a 46.705 posted by Sainz, as Vettel goes second, ahead of Ocon, Zhou and Albon.

A 46.962 sees Gasly go fourth, with Magnussen going fifth moments later.

In quick succession, Alonso, Tsunoda and Hamilton go quickest, the Briton stopping the clock at 46.295.

Sainz responds with a 45.118 as Ocon goes quickest in the final sector.

Courtesy of a two from Latifi, Leclerc goes quickest with a 43.806 as Alonso posts a 44.928 to go second.

After ten minutes the only driver yet to appear is Verstappen.

Perez improves to second but remains 0.733s off Leclerc's pace, as teammate Verstappen finally heads out.

A 45.029 sees Tsunoda go fourth.

Verstappen's first flying lap sees the world champion go sixth (45.343) as Sainz improves to second with a 44.274.

A 44.462 sees Verstappen improve to fourth, as the top four are now covered by 0.656.

21 minutes in and Latifi is the first driver to switch to softs, with teammate Albon following suit moments later.

As Verstappen is told that he's losing out in Turns 2 and 3, Latifi fails to improve on 19th.

The world champion subsequently posts a 43.836 closing to within 0.030s of Leclerc.

More and more rivers now switch to the softs, among them Vettel who improves to sixth with a 44.973.

Russell goes fifth with a 44.548, with Hamilton posting a 44.874 shortly after.

A 44.478 sees Alonso go fifth, the Spaniard looking as strong as ever this weekend.

"The front and rear so weak," says Russell, his voice clearly affected by the bouncing his car is suffering.

The Ferrari pair trade fastest sectors, Leclerc improving to 43.224 while Sainz backs off after making a mistake in Turn 16.

Perez makes the switch to softs, leaving his teammate as the only driver to try the red-banded rubber.

Quickest of all in the final sector, Alonso goes fourth with a 44.142.

"Really lean on these tyres," Perez is advised.

Replay shows Albon kissing the barriers at Turn 17, while Ocon also has a close encounter. Elsewhere, Schumacher has headed down the escape road at Turn 4.

Perez makes use of the escape road at Turn 1 after failing to stop his car. Shortly after, Gasly follows suit while Leclerc is off at Turn 7.

On a flying lap, Verstappen has to abort after Perez went off at Turn 15 bringing out the yellows.

Still 1.050s off the pace, Sainz asks his engineer: "What do we do?"

Attention now turns to Sunday as the longer runs get underway.

Schumacher improves to 19th with a 46.793, the Haas visibly bouncing on the straights.

Stroll is off at Turn 15, bringing out the yellows.

"How is it possible," asks Tsunoda, "I was so close but I couldn't overtake."

A clearly frustrated Leclerc argues with his engineer over what he perceives is a loss of power.

A late brush with the barriers for Tsunoda, while Sainz heads down the escape road at Turn 15.

The session ends. Leclerc is quickest, ahead of Perez, Verstappen, Alonso, Sainz, Gasly, Russell, Tsunoda, Ocon and Norris.

Vettel is eleventh, ahead of Hamilton, Stroll, Ricciardo, Bottas, Zhou, Magnussen, Albon, Schumacher and Latifi.

So while it is pretty much business as usual for Ferrari and Red Bull, not for the first time Mercedes appears to have gone in entirely the wrong direction during the break.

Alonso continues to look good, as do the Ferrari pair, while Norris continues to be McLaren's best performer. At the other end of the timesheets, Alfa Romeo and Haas were both surprisingly off the pace.

Check out our Friday gallery from Baku, here.