One thing to look out for at Ferrari is Vettel's slight helmet change. He's basically got the same design in a more 1970s style and a bit more black on it to make it look retro. Doubt that is enough to get him one of those penalties no-one is really sure about.
Kvyat locks up and goes over the chicane at Nouvelle.
The Lotus drivers are fourth and fifith. The team gives Grosjean a complimentary radio message and tells him to box.
Kvyat currently the best of the rest, on the soft tyre, 1.660s down on Hamilton.
Hamilton shaves another three tenths off his time, lowering the benchmark to 1:16.705. Rosberg crosses shortly afterwards but is 0.566s down on his team-mate.
@RCC: On Wednesday the drivers seemed pretty nonplussed by the changes after their track walks. Will be interesting to ask them again after this session now they've had a chance to drive - but the changes look pretty minimal.
Alonso and Vettel are out on track for the first time. no Raikkonen just yet.
"Keep pushing, keep pushing, one more lap."
"The tyres don't like two laps, dude," says Hamilton in reply. Peter Bonnington tells him to carry on for the tests Mercedes are carrying out.
@ZAC: No forecasted rain yet.
Rosberg complaining about oversteer in the Mercedes.
Raikkonen is now out on track.
@Sandeep: We'll see, this afternoon will be crucial if they do want to get any points. This is where the debate about refuelling becomes interesing - how many teams would do a Toro Rosso and run an FP1-style low fuel run to mix up the order in quali this afternoon? Would certainly add a bit more spice to things.
@Sandeep: Nope, both men are out on track.
@Michael: I don't know if that's completely accurate. In the final sector in Spain, the one which is a good indicator of Monaco, the Mercedes was much stronger than Ferrari and looked much more balanced. People forget what a good aero package Mercedes has delivered, not only this year but last as well.
@ZAC: Nope, Pirelli boss Paul Hembery was talking about that on Thursday in fact. This is what he said: "There’s two schools of thought. Obviously go towards 18/19, closer to the road car. The other thought is that all of our current circuit tyres are 18 inch really, which differentiates, bizarrely, F1 away from what everyone else is going. I think the marketing department would like to keep 13", a nice big sidewall for branding on there we don’t have to pay for. Every cloud has a silver lining. We’ll do what the sport wants, ultimately, we’ve always aid that, we’ll find solutions to what they want."
Button moves into seventh on the soft tyre.
@Michael: Well, we haven't seen a supersoft run from Ferrari yet so I don't understand what you are referring to. Mercedes looks to be clearly quicker than anyone else so far this weekend, though I'm not ruling out a Ferrari on the front row.
Vettel runs across the Nouvelle chicane.
Raikkonen has moved into P3, while Ricciardo is four tenths behind him in fourth. Interesting Ferrari/Red Bull/Ferrari/Red Bull in the pecking order currently.
@Sandeep: Hearing it trackside is bizarre. To be perfectly honest with you, the Honda sounds like it's sick - spluttering through the motions with a really, really odd noise.
@Phil,Maidenhead: That's certainly a concern. What F1 has to ensure is that it doesn't create exactly that situation.
We're seeing the first helmet cam on the FOM broadcast - Stevens has a camera on the side of his helmet. It looked fuzzy but gives you a good indication of how close they get to those walls. More of the same, please, F1.
@RCC: Yes but we have more drivers out there on supersofts now.
Alonso bails out of his latest lap after getting a bit too close to a Ferrari.
Hulkenberg moves into P4 on the supersoft tyre, 1.5s down on Hamilton.
Raikkonen's first supersoft lap sees him stay third - 0.6s down on Hamilton. And he thumps into the barrier at Turn 1! Yellow flags out.
"Ok. I took the rear wheel off," a rather bemused Raikkonen says.
Red flags are out as Raikkonen's car is parked at the bottom of the hill.
Alonso, meanwhile, went fourth with his own supersoft run.
@Phoenix: Hard to say. Magnussen isn't driving in a series at the moment and McLaren will see that - he could have driven in Indycar this year were it not for his last-minute replacement of Alonso in Australia. I think McLaren realises it has two drivers that both need to be driving in F1 next year. A real headache. Personally, I'd love to see them do something a bit different and send them off to Indycar for a year.
@sam: Alonso did a 1:18.197.