Sebastian Vettel: OK, something's not right, I'm losing time down the straights. His engineer Rocky replies: "OK, we don't see anything wrong, please try again."

Vettel comes back: "There was a clear feeling on the straight when I started losing power. Rocky replies: "OK, at the moment, we think it might be a headwind."

Frosty. Vettel is leaving Red Bull at the end of the season, of course.

The order is unlikely to change now as drivers and teams have switched their attention to long-runs to gather data for Sunday's race. One of the aspects they will be looking at is how the tyres degrade and wear on heavy fuel loads so they can formulate strategy plans.

Russian Daniil Kvyat, who is currently seventh quickest, has a bunch of oversteer, but wrestles control of his Toro Rosso and continues. Pictured here on the thermal imaging camera.

Image source, Getty Images

Lewis Hamilton completed another tidy lap and improves his fastest time by two tenths of a second with a 1:39.630.

Nico Rosberg looks set to close the gap on Lewis Hamilton, but then runs wide at Turn 17.

So it looks like the best times on the soft tyres will come after a couple of laps. That could make qualifying interesting as timing - and making space - will be crucial.

Image source, Getty Images

Jenson Button improves on his next lap with a 1:40.718, but he's bumped down by Nico Rosberg. Kevin Magnussen delivers a stunner, to go quickest, but none of them are a match for Lewis Hamilton, who is the first man into the 1m39s with a 1:39.817.

Lewis Hamilton's soft tyre effort is disappointing, the Briton going fourth quickest, two tenths off the pace and behind the two McLarens.

Image source, Getty Images

Nico Rosberg reasserts his authority with a 1:41.027, 0.169 seconds clear of Jenson Button (pictured) in second. Kevin Magnussen then splits them, slotting into second just 0.038 seconds off the pace.

Diesel::Driver: ‏Things not looking good for Kimi. He's only done 5 laps in 30 mins.

McLaren's Jenson Button gains about six tenths of a second by bolting on the soft tyres to go quickest with a 1:41.196.

Nico Hulkenberg does a cooling lap and then goes even faster on that same set of softer tyres. The German clocks a 1:41.677, 0.169 seconds off the pace-setter Nico Rosberg, who incidentally has just gone out.

Tone720:, external Kvyat giving some detailed feedback there, come a long way :)

Sauber's Esteban Gutierrez puts the softer tyres on and improves to an unspectacular 14th place. Force India's Nico Hulkenberg makes better use of them and leaps into fourth, 0.461 seconds off the pace.

Daniil Kvyat: "The car is lazy, it's not responsive, there's no grip, so we'll box."

Image source, AFP

With half an hour gone, Nico Rosberg leads Lewis Hamilton (pictured), with Jenson Button third and Jean-Eric Vergne fourth. Here's the top 10:

1) Ros 2) Ham 3) But 4) Ver 5) Alo 6) Mas 7) Kvy 8) Bot 9) Mag 10) Per

Romain Grosjean: "There is a problem guys, I cannot drive."

It's not often I write this, despite the number of problems he has had this year, but Kimi Raikkonen is bottom of the timesheets 8.4 seconds off the leading pace.

The pendulum swings back to Nico Rosberg in the battle of the Mercedes team-mates as the German clocks a 1:41.508, a quarter of a second clear of Lewis Hamilton.

Replays show that Lewis Hamilton locked up on that last lap, which won't have done that right-front tyre any good.