Andrew Benson
Chief F1 writer in Sochi

"Marcus Ericsson has made a real step forward in the last couple of races in the Caterham. There are a couple of reasons for this, the team believe. One is that he gained a lot of confidence from the Singapore race, where he held off Jules Bianchi's Marussia in the closing laps for 15th place. Ericsson then out-paced his experienced team-mate Kamui Kobayashi in Japan, and is doing so again here in Russia.

"However, the cars are not in the same spec. Kobayashi's crash on his third lap of practice in Suzuka destroyed the only set of new parts available to him, and this new front wing and floor make a significant difference to the car's pace. As the cars have come straight from Japan to Russia, with no facility for extra spares to be introduced because of the logistics here, Ericsson has the new bits and Kobayashi doesn't."

Nico Rosberg moves back into top spot with a 1:40.178 in his Mercedes, having completed 15 laps. Valtteri Bottas then demonstrates that Williams could be Mercedes' closest challenger this weekend as he foes second, just 0.035 seconds off the pace.

Work continues on Pastor Maldonado's Lotus. He's the only driver who has yet to set a timed lap.

Andrew Benson
Chief F1 writer in Sochi

"There has inevitably been a lot of focus here on the accident in Suzuka that left Jules Bianchi with such grave injuries. Governing body the FIA held a press conference, detailing the events that day in Suzuka, with the aid of videos. It transpires that there was an initial brief delay - of about 20 seconds - in scrambling the medical and safety cars after Bianchi's crash because initially race control did not know what had happened.

"That was because Bianchi's car was not visible on the monitors and the systems that indicate to race control that a car has had an accident were destroyed by the size of the impact. But the FIA doctors said that other than that, all the medical and extrication processes were handled seamlessly."

Very committed lap from Valtteri Bottas in the Williams, the Finn moving to the top of the pile with a 1:40.655 on the medium tyres.

With half an hour gone, there's still half an hour to go. Force India's Sergio Perez looks like the first driver to head out on the soft tyre for a qualifying-simulation run.

Drivers were really struggling for grip during Friday practice, the new surface proving to be very greasy.

That remains the case today, with Felipe Massa finding himself with an armful of opposite lock and he grabs control of the rear end of his Williams at Turn 15.

Kamui Kobayashi goes off at Turn Four but continues in his Caterham. Williams' Valtteri Bottas also runs wide there, but no real harm done.

The track is clear and we're back under way.

More bad luck for Pastor Maldonado. He's not going anywhere as his car is up on the jacks while the team change the battery. The Venezuelan has yet to complete a timed lap this morning. His Lotus team-mate Romain Grosjean is 13th.

Andrew Benson
Chief F1 writer in Sochi

"A glance at the circuit map and a walk around the track suggests Turn Three, a long, negative camber left-hander, would be the most interesting corner on the track. But it turns out that is pretty much flat for everyone - and Lewis Hamilton does not even bother to tuck the Mercedes in tight, preferring a wider line.

"The trickiest corner has ended up being Turn 13, one of many apparently nondescript 90-degree right-handers, but this one is at the end of a long straight and with a braking zone through a left-hand kink. There were a lot of locked wheels and cars running wide there on Friday. 'It's bumpy and the left wheel is unweighted so it's very easy to lock it,' Jenson Button said."

Matt Harrod, external: Would love to see Mclaren do well. They have been through the wars this year. #ForzaJules

James Smith, external: Sochi's a street track with all the excitement of a street track taken away. No danger of touching a wall on exit of a corner.

Adam Gardner, external: Am watching #BBCF1 Practice 3 at the #RussianGP near Sochi. Great track; should be an excellent qualifying session! Good luck #lewishamilton

The session will restart at 09:23. While we wait for the marshals to remove the McLaren from the track, here's the top 10:

1) Ham 2) Ros 3) Kvy 4) Vet 5) Hul 6) But 7) Per 8) Mag 9) Sut 10) Ver

And now he's come to a stop. Replays show the rear end just snapped, with Kevin Magnussen suggesting it could be a puncture, and the Dane did very well to catch it and wrestle back control to keep the car out of the wall. The session has been red-flagged.

McLaren's Kevin Magnussen has slowed to a snail's pace, bringing out the yellow flags.

Nico Hulkenberg, who faces a five-place grid penalty after changing his gearbox, goes fifth quickest in the Force India, nine tenths of a second off the pace.

Red Bull's Daniel Ricciardo is the only driver not to venture out on track so far this morning with 45 minutes remaining.

Andrew Benson
Chief F1 writer in Sochi

"It feels more trivial than normal in the circumstances, but there is a grand prix to be run here, of course, and Mercedes appear to be in a race of their own. Lewis Hamilton was nearly a second clear of anyone else on Friday.

"Team-mate Nico Rosberg's pace was less impressive but the two were on divergent set-ups as they analysed the Sochi track and also made a mistake on his quickest lap. The Williams of Valtteri Bottas was quicker than both on the longer runs in the second session, but the 0.35 seconds margin suggests that is not a like-for-like comparison. Expected a Hamilton v Roberg battle for pole later."

Image source, Getty Images

Lewis Hamilton goes quickest with a 1:40.725 in his Mercedes, with his team-mate Nico Rosberg crossing the line shortly after 0.4 seconds adrift.

Mercedes are doing something new this weekend, with Lewis Hamilton and Nico Rosberg pulling out of the garage, stopping after a couple of metres to do a senor system reset, and then accelerating away, reports BBC F1 pit-lane reporter Tom Clarkson. The team won't tell Tom why they're doing it, but it will be related to the team's ongoing push to cut out the reliability issues that have affected them this season.