Whilst Nico Rosberg led the inevitable Mercedes 1-2 in this morning's session, one couldn't help but feel that the Ferrari duo, who unlike the Mercedes pair set their best times on softs not supers, were holding something in reserve.

Indeed, as a further sign of its intent the Maranello outfit is providing both of its drivers with new engines tomorrow having spent even more of development tokens.

Splitting the Williams in sixth was the man who, certainly in the opening few minutes of the session, grabbed the headlines, Daniel Ricciardo, who gave Red Bull's alternative to the Halo device, the Aeroscreen, its much anticipated debut.

Despite the session being held two hours earlier than any other this weekend, it was a busy morning, with Bottas completing 34 laps.

Being held earlier in the year than normal, and with the track seeing little action of note over the winter, it was always anticipated that the circuit would be green, but surely nobody expected the number of spins and errors we witnessed, as Turns 2, 15 and 17, in particular, appeared to catch out even the best... several times.

The air temperature has increased marginally to 16 degrees C, whilst track temperature is 39 degrees.

Two drivers keen to get to work this afternoon will be Marcus Ericsson at Renault and Nico Hulkenberg at force India, both of whom handed their cars over to their team's reserve drivers earlier.

The lights go green and Wehrlein leads the way, followed by Gutierrez, Magnussen, Palmer and Haryanto. Vettel is also keen to get to work, like the previous five drivers, his car is shod with softs.

Gutierrez posts 1:43.156, with Magnussen posting 43.298 moments later. However, both are demoted when Haryanto bangs in a 43.111.

Vettel gets things a little more serious with a 39.326 as more and more drivers head down the pitlane.

As Haryanto makes a hash of T2, Perez goes second (40.428) ahead of Raikkonen, with Verstappen going fourth.

A lock-up for Alonso at T2, a mistake by Massa at T7 and Palmer improves to ninth with a 42.162.

No sooner has Raikkonen improved to second to make it a Ferrari 1-2 than Rosberg splits the pair with 38.926, just 0.005s off Vettel's best.

A mistake at T7 by Hamilton means the Briton is unable to improve on 18th (47.954).

Whilst his teammate continues to struggle, Rosberg goes quickest in S1 however, he runs wide in T10 and consequently fails to improve.

Yet another mistake by Hamilton, again at T7, the Briton really struggling today.

This time around, Hamilton goes quickest in S1, posts a PB in S2 and another purple in S3, crossing the line at 38.311 to go quickest by 0.610. A suitably great lap from the three-time world champion.

As Grosjean complains that "something's not working", Rosberg goes second with a 38.450, just 0.139s off his teammate's pace.

Just to demonstrate that he's not totally on top of things, Hamilton spins at T4. Replay shows him taking too much kerb on entry.

The Ferrari duo now switch to the supersoft for the first time today. Both drivers are slow to 'turn on' the softer rubber, nonetheless, despite only being quickest in S2, Vettel goes quickest with a 38.235, 0.076s quicker than Hamilton. Raikkonen, on the other hand, aborts his first timed lap on the supers. "I will do one extra lap, I ****** it up" says the Finn.

Three PBs see Raikkonen go fourth overall (38.793), as Vettel goes quickest in S1. However, moments later he grinds to a halt on the pit straight, bringing out the Virtual Safety Car. "I've lost the electronics," he reveals.

As his rivals continue, albeit under the VSC, the German is pushed back to his garage.

The replay shows that his electrics suddenly died in the final corner.

Button improves to sixth with a 39.255, just three spots ahead of his McLaren teammate.

As the Maranello mechanics swarm over Vettel's ailing car, Hamilton goes quickest in all three sectors as if to rub their noses in it, the Briton crossing the line at 37.583.

Indeed, as the camera cuts to Vettel on the pit-wall, the German, who is with team boss Maurizio Arrivabene, cuts a forlorn figure.

Despite his best efforts to close the gap to his teammate, Rosberg loses out due to traffic. Meanwhile, it is only a poor S3 that prevents Hamilton increasing the gap.

As Ricciardo goes fifth (39.084) on the softs, Grosjean spins at T8, the Frenchman wasting no time in getting going again.

At 'half-time', it's: Hamilton, Vettel, Rosberg, Raikkonen, Ricciardo, Bottas, Kvyat, Button, Massa, Alonso, Sainz, Verstappen, Hulkenberg, Perez and Magnussen.

On one lap alone, Perez runs wide in turns 2 and 10, proof that drivers are still really struggling.

In the Ferrari garage the crew form a wall in order to prevent prying lenses seeing what's going on as work continues on Vettel's car. Elsewhere in the garage, Vettel is making notes.

With thirty-five minutes remaining, attention has now shifted to long runs on high fuel.

Check out our Friday gallery, here.