Another moment for Vettel, this time at Turn 8.
Hamilton appeared to pull out of that monstrously quick lap earlier.
Rosberg improves to P1, Bottas goes 0.035s behind the Mercedes man.
The new benchmark is 1:40.178, set by Rosberg. Very nice lap from the German.
Williams has really stepped it up a notch this morning. Sorry, McLaren fans.
@RohanMehta: No word, but it seems Red Bull will not be taking it at this race.
Kvyat, still sitting prettily in fourth, has a big lock up at Turn 11.
He runs a little deep into the corner but manages to recover it. With those tyres now shot, he returns to the pits.
As an interesting side note, the pit lane speed has been reduced to 60km/h here. Button and Maldonado both incurred speeding penalties on Friday.
@Kesh: Williams tends to turn the wick up a bit on Saturday. Concentrates on race prep on Friday.
@eastcoastatwork: I think we will see Rossi in the car, as the race is in America. The team will want to defend its position in the constructors' - earnt by Bianchi's ninth place in Monaco - and the best way to do that is with two cars.
Turn 2 a real handful for drivers with Hulkenberg, Vettel and Vergne all running wide there within a minute of each other.
@SiranCousland: Safety is on everyone's mind this weekend but the pit lane is also very narrow, so a reduced maximum speed makes sense.
@Shivam: Nothing since Tuesday's update.
@sfifan: Medium and soft tyres, and that's a well-timed question - because Raikkonen is just about to venture out on the soft tyre for the first qualifying simulation of this session.
Button is told the problem on Magnussen's car does not affect him.
Whoever mentioned it earlier - Alonso has started from fifth position 35 times in his career.
@RohanMehta: Not at all, I just mean they are looking at other data, focusing on their longer run pace. The end result being it doesn't equate to an impressive-looking lap time in Friday practice.
Rosberg and Button out on the softs now so we should see qualifying simulations from here on in. Prepare for some activity up there on the timing screens.
Looks like there may be an issue with Chilton's Marussia, with lots of mechanics crowding around the car.
Magnussen had an early problem, which has limited him to just four laps, while Button's car seemed to be handling a little more erratically than yesterday. Williams has also made a good step up as well.
Raikkonen goes sixth with a 1:41.025. I doubt those soft tyres are ready enough to optimise his lap time yet though. Button goes fourth on his first soft tyre run.
Raikkonen's improvement just over a second.
@jdrafferty: It certainly doesn't suit Raikkonen this year, but Alonso could probably drive a Lada into the points.
Looking more and more likely, isn't it.
April 10: Free practice 1