Ahead of today's second session the air temperature is 30 degrees C, while the track temperature is 37 degrees. It is bright, sunny and very windy.

Very little in terms of upgrades this weekend, basically Alpine has a new floor edge and Alfa Romeo a new floor body, while Mercedes, with its last upgrade of the season, has a new front wing, floor fences and edge and rear wing endplate.

Perez and Zhou both have 5-place grid penalties for Sunday's race after taking on new internal combustion engines, with talk of other drivers taking on new components tomorrow.

Sainz was quickest earlier, ahead of Verstappen and Hamilton, in a session that was remarkably busy.

One of the reasons for this is that this To further aid the Italian manufacturer in its analysis of the results the session will last for ninety minutes.

The experiments tyres are unmarked so that the teams don't know exactly what they are running.

Having handed their cars over to rookies earlier, Leclerc, Ricciardo, Bottas, Magnussen and Latifi will get their first taste of the resurfaced track this afternoon.

The lights go green and Bottas leads the way, followed by Ricciardo, Vettel, Ocon and Albon.

While Bottas and Ricciardo are on mediums, the majority of the drivers emerging from the pits are on the unmarked rubber.

Bottas crosses the line at 40.655 but Ricciardo responds with a 40.474.

Ocon, on the unmarked rubber, goes third with a 42.943 as Leclerc (softs) posts a 38.856.

In no time at all there are 18 drivers on track.

A 38.763 sees Sainz go top as Hamilton goes third, ahead of Perez and Ricciardo.

The stewards have noted that Leclerc, now quickest on a 37.614, performed a practice start in the pitlane.

"I made a small mistake," admits Leclerc, "I need to get into the rhythm."

Hamilton's DRS appears to have a will of its own, opening and closing without any input from the driver, whilst in the Aston Martin garage Stroll is out of his car and not looking like going out anytime soon.

Ocon has also been noted by the stewards for performing a practice pit stop.

While most continues with the prototype tyres, Leclerc, Bottas and Ricciardo have switched to the mediums.

The stewards confirm that no further action is to be taken over the Leclerc/Ocon incidents.

Now on softs, Ricciardo improves to second (37.627), ahead of Bottas. Sainz is fourth on the prototype tyre with a best time of 38.232.

"Hamilton has no mirrors today," complains Alonso after being impeded by his former teammate. "Unbelievable."

Elsewhere, Norris has a big wobble as he enters the pits, the Briton almost clouting the wall with the rear of his McLaren.

The wind and the bumps are catching out a number of drivers including Sainz and Schumacher.

"Something big is loose around my pedals," reports Magnussen, who is told to pit. Of course, this is the car that Giovinazzi crashed in the opening session.

With 50 minutes remaining, Ricciardo switches to the prototype rubber, while Magnussen and Latifi have yet to try the 'normal' tyres.

Leclerc is the last driver to make the switch, as attention focusses on longer runs of 8 laps with a fixed fuel load.

A big twitch in Turn 15 for Norris.

With just under half-an-hour remaining, Ricciardo, Verstappen, Ocon, Alonso, Albon and Vettel have all completed 26 laps which is the set number of lap Pirelli was aiming for.

The TV cameras cut to the Red Bull garage where Brad Pitt is talking to Max Verstappen.

Mercedes is the first team to complete its tyre programme, the German outfit signing off with 10 minutes remaining.

More teams bring their session to an end, leaving Leclerc, Bottas, Ricciardo and Magnussen as the last out.

The session ends, and though the order is pretty meaningless, Leclerc is quickest, ahead of Bottas, Ricciardo, Sainz, Schumacher, Norris, Verstappen, Hamilton, Gasly and Perez.

Magnussen is eleventh, ahead of Tsunoda, Russell, Zhou, Stroll, Ocon, Alonso, Albon, Vettel and Latifi.

Check out our Friday gallery from COTA here.