Ahead of today's first free practice session the air temperature is 36 degrees C, while the track temperature is 22 degrees. Tyres available are medium and soft.

Amongst the myriad of changes that have been introduced this year - far too many in our humble opinion - there have been changes to the practice sessions also, however, they are unlikely to make in impact in these opening races. In particular we mean no third drivers... though it is hoped the teams will take advantage of the extra set of tyres that should ensure running in the first half hour.

After all the talk of Mercedes heading into the season as favourites there is already drama, as the German team has been forced to change Lewis Hamilton's engine. The Brackley squad, which starts this weekend as hot favourites following its pre-season form, identified a fault in one of the ancillary systems late on Thursday night which forced it to swap the unit.

However, as the engine had not left the garage Hamilton will not incur a penalty, nor will the engine count as one of the five allocated for use during the season.

Shortly after the lights go green, Alonso gets the session underway, followed by Sutil, Magnussen, Ericsson and Button.

More and more drivers pour onto the track, though few of them are Renault powered, all but Sutil and Vergne the only drivers staying out for a second lap.

Further drama for Hamilton, his car stops on track with smoke emanating from the back. Less than a lap into the session the hot favourite is out.

As the TV cameras focus on an understandably shocked Mercedes garage, Kvyat heads down the pitlane. Just over ten minutes into the session, all but Vettel, Chilton, Grosjean and Maldonado have made an appearance.

Ricciardo and Magnussen are back on track, the Australian going on to post the first time of the day (season), crossing the line at 1:37.290. Moments later Magnussen posts 37.762 as Ricciardo improves to 35.188.

More drivers take to the track and more times are posted, as Ricciardo raises the bar with a 34.600, Vergne goes second ahead of Magnussen, Rosberg. Shortly after, Alonso posts 33.127 to take the top spot only to be demoted by Rosberg and his 32.784.

A big twitch for Alonso in T4, the Spaniard getting the full 2014 'torquey' experience.

Shortly after Ricciardo has an even bigger moment in T12 whilst Perez gets very much out of shape in T3.

Alonso retakes the top spot with a 32.588.

After half-an-hour, it's: Alonso, Rosberg, Ricciardo, Vergne, Hulkenberg, Magnussen, Bottas, Perez, Kvyat and Button.

While Hamilton appears to be the only retirement, Caterham is also having problems with Ericsson's session over with what is thought to be an electrical issue and Kobayashi suffering a problem with his fuel system.

A 32.893 sees Button improve to third. In the Mercedes garage the team awaits the return of Hamilton's car.

Approaching half-time, only eleven drivers have posted times, of those only the two Toro Rosso drivers are running Renault power units. Vettel and the two Lotus drivers haven't even completed an installation lap.

Despite the talk of engine noise not being too badly affected by the rule changes, fact is you can hear the tyres squealing for the first time in ages. Indeed, Mat Coch reports the TV helicopters are drowning out the sound of the cars.