Ahead of today's opening session, the air temperature is 26 degrees C, while the track temperature is 47.1 degrees. It is bright and sunny.
In a bid to add some spice, Pirelli has brought the softest compounds in its range here, while - other than the on-track action - the main talking point this weekend is whether Mercedes will protest the Red Bulls.
A number of drivers will be looking to make amends for Monaco, among them Ricciardo - a former winner here - and Tsunoda, while Mercedes, still smarting having lost the lead in both championships, will be looking to restore the usual order.
The lights go green and Perez heads out, followed by Ocon and Schumacher. Monaco pole-man, Leclerc, is among the early risers.
As more drivers head out, Verstappen and the Mercedes pair remain in their garages.
Talking of rear wings, Perez is running a very skinny version, while the wing on the Mercedes is much bigger.
Ocon complains that his steering is pulling to the right as the Mercedes duo head out.
Sainz complains of brake vibrations.
Of the first wave, Leclerc is quickest (47.701), ahead of Sainz, Norris, Stroll and Schumacher.
Sainz improves to 46.706, as Ricciardo goes third, ahead of Alonso, Bottas and Norris. Hamilton posts an exploratory 50.564.
A 46.935 sees Gasly split the Ferraris, the Frenchman subsequently reporting that "something smells really hot".
Leclerc retakes the top spot with a 46.321 as Norris improves to second (46.321).
Ten minutes in and Verstappen finally heads out.
Sainz improves to second (45.700), the Spaniard having a very close encounter with the barriers as he pushes the Ferrari to its limit.
Mazepin complains of "a lot of sliding" with his fronts.
The VSC is deployed as a marshal retrieves a piece of debris from the track.
Hamilton subsequently improves to sixth with a 47.411. The world champion goes on to claim the top spot with a 45.112.
Unfortunately it is unclear what compounds the drivers are using as there is an issue with the data.
Verstappen goes sixth with a 46.220. His teammate has yet to post a time having pitted after just two laps.
On softs, Hamilton consolidates his top spot with a 43.893, as Vettel improves to fifth with a 44.861.
A 44.861 sees Verstappen go second, albeit 0.968s off Hamilton's pace.
Tsunoda complains of "loads of understeer" in the slow speed corners.
As he closes to within 0.205s of Hamilton, Verstappen is advised that it is S1 where he is losing out.
A spin for Tsunoda in T4, brings out the yellows as the AlphaTauri driver has great difficulty finding reverse. "I don't know why, but I can't get reverse," he says. "Help!"
As he finally gets going, replays show him clumping the wall before heading down the escape road.
Meanwhile, Perez is back on track and is 14th.
At 'half-time', it's: Hamilton, Verstappen, Gasly, Alonso, Norris, Leclerc, Vettel, Sainz, Stroll and Ricciardo.
Ricciardo is advised that Turns 3, 8 and the final corner are where he needs to improve.
Ah, we have the tyre data... at last.
While Hamilton's best was on softs, Verstappen was on mediums.
On softs, Leclerc goes second (43.921), ahead of Norris who is also on the red-banded rubber.
Ricciardo goes quickest in S1 and again in S3, finally crossing the line at 43.732 to go top. "Well done mate," he is told, "with the traffic you had that was pretty good".
Quickest in the first two sectors, Norris loses it in Turn 16 and spins, the Briton clearly carrying too much speed into the corner and clouting the inside kerb in the process.
No purples but PBs in all three sectors see Sainz go top with a 43.521, only to be demoted when his teammate stops the clock at 43.227.
Looking set for a very good time, Hamilton overdoes it in T15 and heads down the escape road.
Sainz reports that his cool down lap has to be "pretty slow".
Gasly heads down the escape road at T15, a la Hamilton, but unlike his teammate is able to find reverse.
"Unbelievable, unbelievable," sighs Verstappen after coming up behind a slow car that his hogging the racing line. We will not identify the driver, other than to say he's in a Haas and isn't German.
Said driver subsequently reports a clutch issue, though that is hardly likely to impress Verstappen.
Speaking of whom, the Dutchman, now on softs, goes quickest in S1, going on to post a PB in S2. At the line it's 43.184, while Perez goes fourth with a 43.630.
With 7:45 remaining, it's: Verstappen, Leclerc, Sainz, Perez, Ricciardo, Gasly, Hamilton, Norris, Bottas and Raikkonen.
Russell complains that his brake pedal feels a bit long.
A late surge sees Verstappen go quickest in S1 as Mazepin runs wide in Turn 15. "Sorry, my fault," admits the Russian.
Replay shows he lost it, possibly with the aid of the wind, and lightly clouting the barriers.
Turns 15 and 16 appear to be particularly affected by the wind, which is likely to pick up over the next couple of days.
In quick succession Sainz and Schumacher are off at Turns 15 and 4 respectively, which causes havoc for those drivers seeking a late improvement.
Bottas is off at Turn 2 and as he spins the Mercedes around he comes face to face with Norris who has also gone off.
As the session ends, Tsunoda is off at Turn 15.
Verstappen is quickest, ahead of Leclerc, Sainz, Perez, Ricciardo, Gasly, Hamilton, Norris, Alonso and Bottas.
Raikkonen is eleventh, ahead of Giovinazzi, Stroll, Tsunoda, Vettel, Ocon, Russell, Latifi, Schumacher and Mazepin.
Check out our Friday gallery from Baku, here.
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