Ahead of this morning's opening session, the big news - or maybe not - is that Haas has retained both Romain Grosjean and Kevin Magnussen for 2019.

Which, recalling the words of the rhyme Ten Little Indians, that then there were six.

And talking of numbers, there are no less than four reserve drivers on duty this morning, Nicholas Latifi at Racing Point, Antonio Giovinazzi at Sauber, Lando Norris at McLaren and Artem Markelov at Renault.

Both Red Bull drivers and their counterparts at Toro Rosso are facing grid penalties this weekend, though exactly how many won't be clear until we know how many components have been changed. Fernando Alonso will also be taking a penalty.

In Toro Rosso's case this is order that Honda can run its latest update without taking a penalty at its home track in Japan next week.

Ahead of this opening session, the air temperature is 23.1 degrees C, while the track temperature is 25.6 degrees.

Ahead of the green light, there is q queue of cars, headed by Alonso, waiting to go out. Indeed, Red Bull wanted Verstappen to be first out, but McLaren beat him to it.

They head out and while most are on hypers, a few are on ultras and Hartley and Sirotkin on softs.

Just four minutes into the session, all have completed an installation lap, all bar Mercedes that is, neither driver even in his car.

Vandoorne - who has admitted he has "zero percent" chance of an F1 drive in 2019, posts the first time of the weekend, crossing the line at 1:40.121. The Belgian is on the softs.

Hulkenberg complains that his radio is breaking up, as the team confirms that data is not being relayed properly at various parts of the track.

When asked why he is so slow, Ocon says he feels "massive oscillation" if he goes full throttle.

Vandoorne improves to 39.057 as Pirelli warns the track is "very green and very slippery".

Eighteen minutes into the session, Leclerc is the second driver to post a time (39.887), with Raikkonen - who he is replacing at Ferrari next year - posts a 37.063. The Sauber driver is on the ultras while the Finn is on hypers.

Hamilton complains of vibration through his steering wheel, as Bottas posts a 38.435.

Suddenly the session bursts into life, and no sooner has Hamilton posted a 37.238, than the Bulls respond with a 36.977 (Verstappen) and 36.600 (Ricciardo). Bottas subsequently splits them with a 34.691.

A big moment for Norris who loses the rear at T4 after losing grip while in the dirty air of a Sauber and does well to keep it out of the wall.

Ricciardo improves to 35.655 on the hypers, ahead of Verstappen, Hamilton, Bottas and Raikkonen. Vettel, along with Stroll and Ocon, has yet to post a time.

Ricciardo is told to stop for a nose change, which seems a little rude.

On the half-hour, Vettel posts his first time of the weekend, the German going fifth with a 35.839 on the hypers.

Hamilton takes the tops spot with a 35.326, like his teammate he is on the ultras.

"There is something wrong with the balance, check the data, there is so much understeer," complains Leclerc.

Vettel warns of a "variation in power".

Behind the usual suspects, it's the other usual suspects, Hulkenberg currently seventh, ahead of Ocon and Magnussen.

A 34.960 sees Verstappen go quickest on the hypers.

Told he's running out of time - the point at which the extra set of tyres must be handed back - Hamilton is told to pit.

As silence falls over the circuit, that time when the action comes to a halt as the teams hand back the extra set of tyres, it's: Verstappen, Hamilton, Ricciardo, Bottas, Vettel, Raikkonen, Ocon, Hulkenberg, Magnussen and Gasly.

Of the reserves, Markelov is eleventh, Norris 13th, Latifi 15th and Giovinazzi 20th.

After a moment at T2, Ricciardo is told that the team is changing his floor. Back in the garage, smoke is seen billowing from the back of the Red Bull.

Making the most of the lull, Norris and Grosjean head out to enjoy a clear track.

The Frenchman, on hypers, improves to sixth with a 36.855, albeit 1.8s off Verstappen's pace.

Not for the first time this year, Vettel complains of being sent out at the wrong time into traffic.

Following a minor off at T5, Hartley complains that his (front) tyres weren't ready.

Shortly after, Hamilton runs wide in T2 having experienced a similar problem, the Briton having switched to the softs.

Vettel, on the hypers, goes quickest in S2 and again in S3, crossing the line at 34.488 to go quickest by 0.472.

Both Williams are over 4s off the pace, with the Sauber pair over 4.9s adrift of Vettel.

Bottas follows his teammate's example in running wide in T2. Meanwhile Hamilton is told there is still some speed to be found in T8.

On the softs, Hamilton improves to 34.818, but moments later Verstappen (hypers) responds with a 34.538.

A spin for Stroll in T18, the Canadian subsequently heading back to the pits.

Currently 11th, with 20 minutes remaining, Raikkonen heads out on ultras.

As work continues on Ricciardo's car, it is clear the Australian's session is at an end. Sceptics - of which there are a few in F1 - might note that the Australian's fortunes have faltered ever since he announced his move to Renault.

A spin for Verstappen at T7, "I lost the rear," he admits, the youngster having done his brand new sets of hypers little good.

Raikkonen improves to 8th with a 36.203, 1.715s off his teammate's time.

Verstappen is told that Vettel's slow lap was 15s slower than his own, the Dutchman minded to keep his slow lap "relatively slow".

Leclerc runs wide in T8 as Giovinazzi improves to tenth with a 36.712. Moments before, Leclerc had gone 13th with a 37.054.

"Same as lap one," replies Ocon when asked about the state of his tyres. He's currently on his 8th lap on his ultras.

"We have a problem with the car," Hulkenberg is told, "we need to box the car now."

Leclerc asks the team to check the data as he continues to experience issues in T8. The youngster revealing that he is "losing the rear all the time".

Along with Vettel, the Bulls and Haas duos have only run the hypers in this session.

The session ends. Vettel is quickest, ahead of Verstappen, Hamilton, Bottas, Ricciardo, Ocon, Raikkonen, Magnussen, Hulkenberg and Giovinazzi.

Grosjean is eleventh, ahead of Gasly, Norris, Leclerc, Markelov, Vandoorne, Latifi, Sirotkin, Hartley and Stroll.

Early days, but heading the timesheets in the opening session will be a early confidence boost for Vettel however, we have yet to see the Mercedes pair on the hypersofts.

Hopefully, with F2 taking place during the break between the F1 sessions, the track will rubber in a little more, a number of drivers having problems with the green, slippery conditions in this opening session.

Check out our Friday gallery from Sochi, here.