Caterham say that the reason for Kamui Kobayashi's retirement was that "his brakes were overheating and it was too dangerous for him to carry on racing". That's slightly different to what the Japanese drive said in a BBC Radio 5 live interview. See entry just after lap 34.

If things stay as it is, Mercedes will be crowned constructors' champions today with three races to go.

Lewis Hamilton leads Nico Rosberg by 18.7 seconds. Replays show Hamilton locking up into Turn 13, but he keeps it on track and it doesn't look like there's much damage done.

David Coulthard
BBC F1 co-commentator

"I wonder if that series of slower laps from Bottas was just because he was overdoing it on fuel so had to pull a bit back and nothing more serious."

McLaren's Jenson Button is told that the team think all cars will now try to go to the end with 10 laps to go. The Briton is currently fourth, 5.9 seconds behind Valtteri Bottas and 12 secs clear of team-mate Kevin Magnussen. Lewis Hamilton leads by 18.6 seconds.

Valtteri Bottas is now starting to close on Nico Rosberg. Is it game on for second place again? The gap is down to 5.5 seconds.

Red Bull team principal Christian Horner on BBC One: "It's not stellar at the moment we have got a bit of a Mercedes procession ahead of us but we are closing on Alonso."

Image source, AP

Lewis Hamilton ups the pace, to remind team-mate Nico Rosberg who is boss in this race, with a new fastest lap. The Briton clocks a 1:41.853 to extend his advantage to 18.5 seconds with 12 laps to go.

1) Ham 2) Ros 3) Bot 4) But 5) Mag 6) Alo 7) Vet 8) Vet 9) Rai 10) Per

Lewis Hamilton responds to Nico Rosberg's pace with a lap in high 1m42s. The gap is back up to 17.6 seconds.

Meanwhile, Mercedes ask Rosberg if he thinks he can get to the end of the race on these tyres. "Easy," comes the reply, before he adds: "Well not easy but I can get to the end."

Russian president Vladimir Putin rocks up in the Sochi paddock to be met by F1 boss Bernie Ecclestone. Nice of you to join us, Mr President. Still 14 laps to go.

Jennie Gow
BBC Radio 5 live pit-lane reporter

"F1 boss Bernie Ecclestone and about 17 burly bouncers have come down to the front gates of the track, along with the world's media. We are expecting Russian president Vladimir Putin any minute."

Nico Rosberg continues to pump in the lap times, the German now 16 seconds behind Lewis Hamilton and 6.6secs clear of Valtteri Bottas. Meanwhile, Sergio Perez and Felipe Massa both pass Jean-Eric Vergne for 11th and 12th respectively.

Toro Rosso are really struggling for race pace at the moment, perhaps they focused too much on qualifying speed. Daniil Kvyat tries a move on Nico Hulkenberg, but locks up heavily and goes off track. "I've got massive vibrations," reports the Russian, who started fifth but is down in 15th.

Valtteri Bottas is told by his team that Nico Rosberg is pushing because he has to make another stop. That would explain why the German is around 1.2 seconds quicker than Bottas at the moment. He's also 17.4secs behind Lewis Hamilton.

Jennie Gow
BBC Radio 5 live pit-lane reporter

"I've been talking to some of the Marussia guys as to why Max Chilton retired. Max was not comfortable in the car [he reported a problem with the car going into Turn One]."

Ibraheem Khan:, external Damn. Rosberg has worked hard for that second place but I was hoping it was the end of his race. We'll see what happens!

Ben Silveston:, external Rosberg has proved me wrong - great recovery drive! WDC title-race is still very much on!!

Mighty Joe:, external Rosberg is a man-possessed! How much longer can those tyres last?

It's another fastest lap from Nico Rosberg, who seems very comfortable on those medium tyres, which have now done 33 laps. The German is still 19.4 seconds behind.

Meanwhile, Sergio Perez passes Daniil Kvyat for 12th. Felipe Massa gets in on the act and slips through, too, to demote Kvyat to 14th.

Caterham's Kamui Kobayashi, who has retired, talking to Jennie Gow on 5 live: "Nothing wrong with the car. The team asked me to stop the car to save mileage.

"We have a lot of mileage limitation to avoid things going wrong with the parts. This is why I get message from top management… I expect to race in Austin."

Caterham have been struggling financially following the takeover of the team from QPR owner Tony Fernandes earlier in the season.

Nico Rosberg is flying, the German clocking the fastest lap of the race to reduce the gap to Lewis Hamilton to 19.7 seconds.

Valtteri Bottas is third with Jenson Button fourth and Kevin Magnussen fifth.

Valtteri Bottas is told not to worry about Nico Rosberg making a pass because they believe Rosberg will suffer with degradation later in the race. Meanwhile, Romain Grosjean is handed a five-second stop go penalty for causing a collision with Sutil earlier.

David Coulthard
BBC F1 co-commentator

"I think once he had committed to it Rosberg had to go for it. When it comes to incidents like that it is a case of I am going through anyway and if you turn in we will have contact and if you don't then thank you very much."