@MasIgnotum: At this stage or pre-season mileage is a better indication of potential than outright pace, I would say.
It's really noticeable it's Button and not Alonso in the car today - the crowds are much thinner than they were yesterday.
Vettel continues to pound out the laps. He's lowered the benchmark to 1:20.984.
That time is set on the medium tyre. Vettel picking up where he left off yesterday so far this morning.
Nasr completes a lap and returns immediately to the pit lane.
Very busy track now - Hamilton, Verstappen, Bottas and Vettel all circling.
Strange. Kvyat has just come down the pit lane ....... without a front wing.
I know Adrian Newey thinks outside the box but this?
As Nate reports, the Red Bull left the pits sans wing for a single lap. Very odd and caused a huge amount of scratched heads here in the media centre.
Not surprisingly, Kvyat came straight back into the pits without that front wing.
Kvyat goes out again in the front wing-less RB11. Interesting stuff from Red Bull.
Some nice eye candy in the paddock.
You can see the front-wing-less Red Bull there.
@RacingFan: I don't think Mercedes cares much about what Vettel or anyone else is doing. Its own run plan will be the main priority today.
@Brambilla: Worth remembering its only the second day of testing. Williams was always pretty off the pace on Fridays last year in terms of headline times, but would always be doing a very different run plan to its rivals. Important not to read too much into times just yet.
@manish: No sign of them yet.
Hamilton and Nasr are the men out on track, but both are lapping pretty slowly. Hamilton is currently lapping between the 1:26 and 1:28 mark at the moment.
Verstappen, by contrast, is lapping in the 1:26s. Once again Mercedes is leading the way in mileage.
@ansarmeeran1990: At the moment there's very little to report on. Button has completed just two laps and we haven't seen any more of them yet. Teething problems were expected.
The track falls silent as Hamilton returns to the pits but that lull is broken by the return of Kvyat - and once again his RB11 has no front wing.
@FishFace0212: Tyres are of less importance on a track like this - the more important tyre runs will come at Barcelona. As for tyres allowed, I thought I had a tweet saved somewhere and I don't and now I'm doubting myself, let me confirm with a colleague and get back to you. It's Monday!
@Sid: Well cast your mind back to 2014 and you'll remember Red Bull completing only 22 laps in four days of Jerez testing last year.
Bottas is now out on track with a massive sensor on the side of his Williams.
Kvyat came back to the pits after its outlap, by the way - unsurprisingly Kvyat was way off the pace without a front wing. That'll be an interesting question for Christian Horner this evening.