Ahead of today's opening session, the air temperature is 23.3 degrees C, while the track temperature is 44.8 degrees. It is dry but overcast, with a 40% chance of rain. Indeed, thunderstorms are predicted over the course of the weekend.
The lights go green and in in no time at all there are 15 drivers on track, among them the Mercedes duo and Perez.
"I have a stuck throttle," complains Sainz following a significant lock-up. "Before I start to push I need to know if something is wrong," he adds. He is advised that the team don't see any issues.
A spin for Kubica at Turn 3, the pole at the wheel of Raikkonen's alfa.
Of the first wave, Hamilton goes quickest (7.809), ahead of Leclerc, Ocon and Vettel, however, a 7.454 sees Verstappen go top.
Ocon complains that something is moving around at the side of his seat.
Hamilton improves to 7.056 but Verstappen responds with a 6.936.
Russell is the last driver to post a time, while Verstappen and Hamilton are on mediums, the quickest hard runner is seventh-placed Giovinazzi.
Ocon has his time deleted for exceeding the track limits at Turn 9. Turn 10 is the other corner where the FIA is clamping down.
Verstappen improves to 6.649 but has his time deleted for running wide in Turn 10.
Once again, Ricciardo is being talked through his laps.
Perez goes third with a 7.066, ahead of Leclerc, Ocon, Tsunoda, Ricciardo, Norris, Giovinazzi and Alonso. The Spaniard, on hards, subsequently improves to fourth with a 7.182 only to have his time deleted.
A 6.640 sees Gasly go second... and it's legal.
Sainz, having been in the pits for some time, heads out again. He is currently 20th, his best time almost 8s off the pace.
Vettel improves to 8th (7.310) on the mediums as teammate Stroll seeks to improve on 15th.
Following that frenzy of early activity, things have died down a little and with 40 minutes remaining there are just 5 drivers on track.
Hamilton and the McLarens head out on softs.
More problems for Sainz who has spun exiting Turn 1 and come to a stop at the pitlane exit.
On the red-banded rubber, Hamilton posts a 6.390, just 0.121s better than Verstappen's best on mediums.
Bottas can only manage fourth (6.721) on the softs, while Leclerc goes ninth (6.896).
Bottas subsequently improves to 6.386 to take the top spot, demonstrating that the softs are good for two hot laps.
Moments later Hamilton bangs in a 6.332, taking full advantage of the kerbs in the final corners.
Meanwhile, the Bulls head out on fresh softs, leaving Ocon and Stroll as the only drivers still to make the switch.
Gasly goes quickest with a 6.166 while Perez aborts his lap after encountering traffic.
Verstappen posts 5.910 and while Bottas looked set to improve a poor final sector meant he failed.
So, Verstappen heads Gasly, with Hamilton third, ahead of Bottas, Tsunoda, Alonso, Ocon, Stroll, Giovinazzi and Leclerc.
Complaining about a slow Latifi, Verstappen is told to "stay calm". Shortly after, Gasly is equally unhappy with Sainz. Fact is, traffic is always an issue here.
Perez says that he lost the fronts at the end of his lap. The Mexican subsequently spins at Turn 4.
Ricciardo has completed the most laps thus far (28), ahead of Bottas (27), Hamilton, Tsunoda, Alonso, Leclerc and Norris, all on 26. Schumacher (21) has completed the least.
As attention turns to long runs, Verstappen, Hamilton and Tsunoda switch from the softs to mediums.
"There were actually some forecasts of rain today," says Pirelli, "which is why we're seeing the run plans slightly condensed this morning. Just in case it pours down during the afternoon..."
As the clock ticks down, with less than a minute remaining, all bar Latifi are on track.
The Ferrari pair are separated by just one-thousandth of a second.
The session ends. Verstappen is quickest, ahead of Gasly, Hamilton, Bottas, Tsunoda, Alonso, Ocon, Stroll, Giovinazzi and Leclerc.
Sainz is eleventh, ahead of Ricciardo, Perez, Vettel, Russell, Norris, Latifi, Schumacher, Kubica and Mazepin.
Check out our Friday gallery from Spielberg, here.