Approaching the half-hour mark of an as expected busy session. It is Valtteri Bottas leading the way, ahead of Felipe Massa, Kimi Raikkonen and Sebastian Vettel.

Out of the leading quartet it is just Vettel on the soft tyres.

Tom Clarkson
BBC F1 pit-lane reporter

It is a Williams one-two at the moment, with Valtteri Bottas still leading the way, his best lap three tenths quicker than Felipe Massa's.

A slightly nervy moment for Bottas, though, as he locks up at the entry to the pit lane, but he keeps it together.

An oversteer moment for Max Verstappen coming out of the last corner and he finds himself off the track and pointing the wrong way. He lets a Ferrari pass before righting himself and getting back on his way.

Image source, BBC Sport

I've just seen a flash of red depart the Ferrari garage. Kimi Raikkonen and Sebastian Vettel have both joined the party after letting others clean up the track.

Raikkonen has gone out on the supersoft tyre, with Vettel on softs.

Valtteri Bottas holds then record for the fastest lap in Sochi, clocking 1:40.896 last year.

He has improved again with a 1:40.617 to maintain his place at the top of the standings.

Nico Rosberg slides wide at the penultimate corner but has the third fastest time at the moment with 1:43.836, putting him behind early pacesetter Valtteri Bottas and Romain Grosjean.

Rosberg drops down to fourth as Lewis Hamilton gets up and running with a 1:43.384. He is second fastest.

Eighteen cars out on the circuit now - just the Ferrari pair of Sebastian Vettel and Kimi Raikkonen waiting a little longer - Valtteri Bottas is one of several drivers to crack straight on with a timed lap, clocking 1:42.829 to go top of the timesheet. That will change soon enough, you would imagine.

It is a mixed bag of strategies to kick things off 11 drivers heading out on softs and six on supersofts.

Nico Rosberg and Lewis Hamilton have both gone out on softs.

One hour of practice is under way and no surprise to see a queue of cars heading out, Daniil Kvyat is at the front of the pack.

Tom Clarkson
BBC F1 pit-lane reporter

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Image source, Getty Images

Lots for us to chat about today, so get involved! Murray Walker turns 92, what's your favourite Murray moment?

The Russian Grand Prix also marks Fernando Alonso's 250th Grand Prix weekend, what, for you, is the stand out race of his career?

And finally, Red Bull. What do you make of the situation? Does F1 need them in 2016? 

Send in your thoughts on any or all of the above to #bbcf1,, external text in on 81111 (UK only) and post your comment on the BBC Sport Facebook page.

Andrew Benson
Chief F1 writer

“The lack of track action on Friday meant conversation was focused on off-track matters, but that would have been the case no matter what, considering the remarkable nature of the behind-the-scenes politics at the moment. 

"The key focus is Red Bull and their struggles to find an engine supply deal for next season, which is wrapped up in doubts about whether they will even be on the grid in 2016. We wrote an extensive article detailing how Red Bull got into this situation on this website last week. Suffice it to say here that, after heavily criticising current partner Renault all year, and getting almost to the point of inking a deal severing their contract, it now seems Red Bull may have to continue with the French manufacturer after all, having failed to get what they wanted out of either Mercedes or Ferrari. 

“Daniel Ricciardo described this on Friday as ‘one of our better options for now’. However, Renault Sport boss Cyril Abiteboul said: ‘Frankly when you see the way we have been treated, it's going to be a very difficult sell to my board and to my executive management to do something else to what is currently planned.’ 

“You just couldn’t make it up.”