As is so often the case, this morning's session posed far more questions than it answered.

While there was no doubting the speed of the Mercedes, one has to wonder why the 0.849s gap between Bottas and Hamilton, neither of whom used the supersofts.

Then there were the Ferraris, both over 0.9s off Bottas' pace and that was on the softer rubber.

While Verstappen was fourth, splitting the Ferraris, the true form of the red bull is difficult to assess not only because neither driver tried the red-banded rubber, but because Ricciardo was one of a number of drivers caught out by the new track surface and windy conditions, the Australian spending much of the session watching from the sidelines.

While Alonso was an impressive sixth, and teammate Vandoorne ninth, are we really to believe that the pace of the Renaults and Force Indias was representative. We think not.

Languishing at the very foot of the timesheets was Williams, and sadly it is unlikely that the Grove outfit was doing a Renault or Force India and holding back, while one has to sympathise with Robert Kubica as he attempts to make his come-back with a team that is clearly on the descendent.

Hopefully, over the course of the next ninety minutes some of those questions might be answered, especially later in the session when attention turns to Sunday.

Ahead of this afternoon's session, the air temperature is 24 degrees C, while the track temperature is 41 degrees.

Over the course of the break Magnussen has been up before the stewards, the Dane receiving a reprimand for a late incident involving Leclerc.

Grosjean is first out, followed by Magnussen and Sirotkin.

The Frenchman posts 21.454 to get things underway, and as more drivers head out it's a mixture of softs and mediums, only Sirotkin on the supersofts.

Magnussen posts 21.164, the Dane, unlike his teammate, on softs.

"Oh fudge," says Grosjean who is off at T7 and embedded in the kitty litter.

The replay shows him carrying just a little bit too much speed into the corner and then the rear end stepping out. After that, he was just like Iggy... a passenger.

The VSC is deployed.

When the VSC is withdrawn, the Red Bull and Mercedes duos are first to head out. While the Bulls are both on softs, Hamilton is on soft and Bottas medium.

Vettel (softs) posts 19.421 to go quickest, with Ricciardo going second ahead of Ocon and Magnussen.

As Verstappen goes quickest with a 19.050, a wobble from Hamilton means the Briton can only manage 2.042.

A 19.216 sees Bottas go second, just 0.166s off Verstappen's pace.

Hulkenberg reports that the winder is stronger than in FP1.

Verstappen improves to 18.699 while Hamilton and Bottas also improve, the Mercedes duo within 0.004s of one another. Bottas, remember on the mediums, and his teammate on softs... impressive pace from the Finn.

Going purple in all three sectors, Hamilton crosses the line at 18.259, leapfrogging Verstappen by 0.440s.

With Vandoorne yet to appear, the Williams duo remain rooted to the bottom of the timesheets, both over 3.5s off the pace.

In the meantime, Raikkonen has gone fifth and then third, the Finn posting 18.829 on the softs.

Behind the big six - or three depending on how you look at it - Magnussen is seventh, head of Ocon, Perez and Alonso.

So while Force India is where we expected it to be following this morning's testing, Renault has yet to show its hand, Sainz currently 13th and Hulkenberg 15th.

As Ricciardo improves to second with a 18.392, the cameras cut to the Ferrari garage where Charlie Whiting is taking pictures of the mirrors on the Ferrari, as Jo Bauer looks on. As we said in FP1 this is essentially now an aero device.

Bottas switches to the supers - the first time for Mercedes today. While he only posts a PB in S1 he goes quickest in S2. A mistake in the final sector however - possibly a gust of wind at T13 - means he can only manage third (18.882).

Now Hamilton heads out on the supers. Like his teammate he has a poor opening sector. However, his mistake is in the second sector, the Briton getting it wrong and running wide.

Finally out on track, Vandoorne, on the softs, posts 19.996 to go ninth.

Verstappen posts a PB in S1 but like Hamilton makes a mistake in the second sector and subsequently backs off. That's two, three drivers, clearly struggling on the softest compound.

Now on the supers, Verstappen goes third witrh a 18.533, just 0.274s off Hamilton's pace.

Around halfway through the session, it's: Hamilton, Ricciardo, Verstappen, Bottas, Raikkonen, Vettel, Vandoorne, Magnussen, Perez and Alonso.

On the supers, Hulkenberg can only manage 14th (20.584) and Sainz 16th (20.672), Renault clearly struggling.

No such issues for Force India, which is currently running 9th (Perez) and 12th.

On his supersoft run Vettel encounters traffic in S3 and subsequently backs off.

Raikkonen goes off at T4 and following a brief run through the kitty litter and then the grass is able to continue.

Next time around he has a strong opening sector, but the moment he begins to up the pace the car is clearly struggling for grip.

"Stop the car, stop the car," Raikkonen is ordered. Somehow, however, the Finn is able to coast back into the pitlane. Ever the professional.

Replay shows a puff of smoke from the rear of the Ferrari just before Raikkonen was given the "stop" order.

As it ends for the Iceman, so it begins again for the Fudgeman, Grosjean back on track following his earlier off. Keen to catch up on lost time the Frenchman is on supers and straight into his qualifying sim.

He subsequently improves to ninth with a 19.766.

Unhappy with the grip - or lack of it - from the supers, Hamilton wants to know what tyres the Ferraris are on, he is disappointed to learn that they too are on the red-banded rubber.

A practice pit-stop for Hamilton who switches to softs, the Briton keen to shed the supers as soon as possible.

On the yellow-banded rubber Hamilton is clearly far more comfortable, setting a strong pace. Teammate Bottas is also on a strong pace on the mediums.

Leclerc runs wide in T4, with Vettel following suit shortly after.

Further down the timesheets, on their race sims, Vandoorne, Perez and Hulkenberg are showing good pace.

Ricciardo and Verstappen follow Hamilton's example and switch to the softs. Magnussen and Ericsson also.

"Drivers are now settling into long runs as part of their race simulations," says Pirelli, "vital preparation for the grand prix. All three compounds currently out on track."

Check out our Friday gallery from Barcelona, here.