Ahead of today's opening session, the air temperature is 15.8 degrees C, while the track temperature is 29.1 degrees. It is bright and sunny, as opposed to the usual 'smog'.
The lights go green and Magnussen leads the way, followed by Grosjean, Albon, Vettel and Gasly.
On his out lap, Kvyat reports that his steering wheel is not straight.
While most complete the one lap, Gasly stays out for a second, the Frenchman one of several drivers who need a good race this weekend. His Red Bull is running an aero rake at the Austrian team seeks to sort its aero issues.
Five minutes in and all bar the Mercedes pair have made an appearance.
Confusion at Renault as Hulkenberg reports that his pitlane speed limiters is limiting his car to 60 km/h rather than 80.
Despite the limited running so far there's been a good mixture of the mediums and hards, while only one driver (Hulkenberg) has run the softs.
For reasons known only to themselves, the teams opt to take a breather, and the track falls silent. After more than twelve minutes of nothing, an engine fires up, it's the Mercedes in the back of Kubica's Williams. He is followed by teammate Russell and Raikkonen.
Kubica posts the first time of the weekend, the Pole stopping the clock at 1:41.339. Moment later, Russell posts 40.725.
As Norris, Kvyat and Stroll head out, Raikkonen posts 40.654 to go top, albeit only 0.071s quicker than Russell.
No sooner has Russell improved to 39.636 than Norris posts 38.250 to go quickest.
Twenty-five minutes into the session, Hamilton finally heads out, dutifully followed by his wing... err, teammate.
Magnussen goes quickest (36.565) ahead of his Haas teammate, the American team looking to resolve the tyre-based issues that plagued it in Bahrain.
A 35.988 sees Vettel go straight to the top of the timesheets, while Ricciardo goes third and Sainz fifth.
Leclerc posts 36.446 to go second, like his teammate he is on the mediums. He reports that his dash is not showing the correct temperatures.
Hamilton's first lap is a 50.710, while Bottas posts 2:00.110. However, next time around they improve to 35.572 and 35.696, respectively. Both are on the softest rubber.
Vettel improves to 35.395, as Giovinazzi is the only driver yet to post a time.
On the hards - yes hards - Verstappen goes second with a 35.513.
A spin for Stroll in the final corner, "I need more temp in the tyres," he complains, "they're freezing cold."
Gasly posts 36.107 to go sixth, like his teammate he is on the softs.
Hamilton (35.102) and Bottas (35.145) both improve to go first and second.
Pirelli admits that it is "surprised" by how early Mercedes has gone soft, and finds it "very interesting" that Vettel, on the mediums, we nt quicker.
Bottas advised of a headwind into T6, and a tailwind on the pit straight.
As we reach that time when the extra set of tyres must be handed back, it's: Hamilton, Bottas, Verstappen, Vettel, Perez, Leclerc, Gasly, Hulkenberg, Sainz and Grosjean. Still no time from Giovinazzi who has only completed 2 laps.
Following another ten minutes of nothing, once again it is the Williams duo that breaks the silence. Both are on the mediums.
Russell improves to 37.619, ahead of Raikkonen, with Kubica also leapfrogging the Finn to leave the Alfas in 19th and 20th.
Ricciardo heads out and is subsequently followed by Albon, the Australian on softs, the Thai on mediums.
As more and more drivers head out, it's a mixture of softs and mediums.
Kubica told to "concentrate on dropping the rear temperature".
On the softs, Raikkonen improves to ninth with a 36.031, as teammate Giovinazzi is out of his car and watching the action on the monitors.
Still on the softs, albeit brand new softs, the Mercedes pair are looking set to improve.
Leclerc, on the mediums, goes top with a 34.167, but is almost immediately leapfrogged by Hamilton who posts 34.118. However, Vettel, also on the mediums, responds with a 33.911.
A 35.447 sees Kvyat go seventh, ahead of Stroll, Gasly and Grosjean.
Though he's not giving away any specifics, it appears that changes to Ricciardo's car have not improved its balance. Nonetheless, the Renault driver improves to fifth with a 35.239.
Verstappen heads out on the softs, while teammate Gasly sticks - no pun intended - with the mediums.
PBs in the first two sectors are followed by a poor final sector, nonetheless Verstappen improves to fourth with a 34.334. Teammate Gasly can only manage 35.428 which leaves him seventh, behind Ricciardo, albeit on the mediums.
Stroll and Kvyat have the track to themselves with 14 minutes remaining.
The Mercedes pair head out again, both, once again, on new softs, as the Ferrari pair persist with new mediums.
Verstappen aiming to do six timed laps on his brand new softs.
Other than the Ferrari pair, who are first and third, the next highest runner on mediums is Gasly, who is seventh, ahead of Kvyat and Stroll, who have also posted their best times on the yellow-banded rubber.
Given advice by his engineer Pete Bonnington, Hamilton responds: "I don't need coaching Bono".
Unlike Leclerc, who asks his engineer to advise him if there is anyone around when he performs his next practice start.
The session ends. Vettel is quickest, ahead of Hamilton, Leclerc, Verstappen, Bottas, Ricciardo, Gasly, Kvyat, Stroll and Grosjean.
Magnussen is eleventh, ahead of Hulkenberg, Norris, Albon, Raikkonen, Sainz, Perez, Kubica, Russell and Giovinazzi.
Check out our Friday gallery from Shanghai, here.