Ahead today's opening practice session the air temperature is 23 degrees C, while the track temperature is 38 degrees. Like last week in Hockenheim, it is hot.

Being the last race before the summer break one would be forgiven for expecting a bit of a 'last day of term' atmosphere, instead it is business as usual, the Mercedes duo battling for supremacy and Felipe Massa still raging over that clash with Kevin Magnussen.

There will are two DRS zones sharing a detection point 5m before Turn 14. The activation points are 130m after the apex of Turn 14 and 6m after the apex of Turn 1.

Tyre choices this weekend are medium (prime) and soft (option).

A four-time winner here, Lewis Hamilton will be looking to make it five this weekend and thereby take the championship lead for the second time this season.

Despite joining Marussia as Reserve Driver, Alexander Rossi doesn't get an outing this morning indeed, there are no reserve drivers on duty. Then again, the tight, twisty nature of the circuit, not to mention its 'greenness', means that teams won't want to take any risks.

Like Monaco, downforce is a real necessity here, so Williams might not be as competitive as it was in the last two races. The absence of FRIC should be more noticeable than it was at Hockenheim also.

The lights go green and Perez leads the way, followed by Bottas and Vergne. With a 'free' set of tyres we will see more running in the opening thirty minutes.

Problems from the outset for Chilton who is running a new chassis. As he heads down the pitlane following his installation lap there is smoke billowing from the back of his car, even a few flames. Mechanics and marshals get to work with extinguishers.

Five minutes into the session all bar the Mercedes duo have been out… at which point Nico and Lewis duly oblige. Indeed, they both post times, Rosberg a 28.754 and Hamilton 31.426. The Briton subsequently improves to 29.703.

Despite a little mistake by Hamilton the Silver Arrows duo continue to make the most of an empty track. Elsewhere, Marussia claims the smoke was due to oil leaking on to an exhaust pipe.

Suddenly the track is alive with action, as the Mercedes duo head back to the pits seemingly everyone else replaces them.

Ricciardo posts 28.534 to go third, ahead of Alonso, Raikkonen and Bottas.

Twenty-two minutes into the session, all but Grosjean, Ericsson and Chilton have posted times.

Kvyat, after just 4 laps is struggling with his tyres, as is Hulkenberg.

As ever, the track, which is not used during the year, is dusty, dirty and green, consequently there are plenty of 'moments'.

Vettel, currently thirteenth on 29.428, complains that his dashboard readout isn't working.

A 27.463 sees Raikkonen split the Mercedes duo while Button, who has fond memories of this track and has therefore reverted to his pink Silverstone 'Papa Smurf' tribute helmet, posts 27.904 to go fourth.

As the opening 'free' half hour comes to an end, the track clears and the engines killed.

Rosberg heads Raikkonen, Hamilton, Button, Ricciardo, Alonso, Vergne, Vettel, Magnussen and Maldonado. Chilton remains the only driver yet to post a time.

Once again, taking advantage of the lack of action, Rosberg heads down the pitlane.

As Rosberg, still alone on track, improves to 25.997, Marussia reports that it is changing the gearbox on Chilton's car and hoping to get him out again before the end of the session.