Ahead of today's opening practice session, the air temperature is 16 degrees C, whilst the track temperature is 22 degrees.

There are only a few changes to the circuit since last year, the kerbs having been renewed and drainage improved at Turns One, Two, Four, Five, Nine, 12 and 15, the work carried out over the winter in time for the pre-season testing.

As for the DRS zones, the first has a detection point 86m before T9 and an activation point 40m after, whilst the second detection point is at the Safety Car line, with activation 157m after T16.

Talking of changes, after all the talk, today actually sees Max Verstappen in the Red Bull and Daniil Kvyat back in the Toro Rosso. Furthermore, Esteban Ocon is on duty for Renault in this session, the French youngster replacing Jolyon Palmer.

The changes extend to the cars also, nearly all of them featuring a whole raft of updates, including new wings, floors and pretty much everything else. Indeed, the only team not running any updates is Sauber, which will also miss next week's two-day test.

Tyres available this weekend are hard, medium and soft. The hard is seen for the first time this year, but no driver has chosen more than one set. The medium, is a v versatile tyre that is a good compromise between performance and durability while the soft, though more than a second faster, is unlikely to last for long.

The lights go green and Gutierrez leads the way, followed by Grosjean, Raikkonen, Verstappen, Ocon and Nasr.

Kvyat is among the last to make an appearance, the Russian having taken part in a rigorous routine earlier this morning, including some boxing.

All running this far has been on hard and mediums.

Last out are the Mercedes pair, the silver car featuring no significant updates this weekend... then again, does it need them?

As sign of his obvious intent, Hamilton posts the first time of the day, a 1:29.834. However, as a sign of his intent, Rosberg responds with a 26.951.

Following his trials and tribulations in China and Russia, Hamilton is using a new MGU-H this weekend, his third of the season.

On the mediums, both drivers continue, Rosberg getting down to 25.456 and Hamilton 25.931.

On and on they go, Hamilton closing to within 0.002s of his teammate, as their rivals look on.

Ericsson is the third driver to post a time, the Sauber driver stopping the clock at 29.945. moments later, Hulkenberg posts 28.555 and Nasr 28.595.

A 25.635 sees Raikkonen go third, the first driver to post a time, or complete a lap, on softs. Nonetheless, he's 0.254s off Rosberg's pace.

Following a cool down lap, Raikkonen goes quickest in S1 but a poor final sector means he can only improve to 25.616.

A big lock-up for Verstappen at T1 who subsequently runs wide and returns to the track sporting a massive flat-spot.

Posting their first times of the weekend, Bottas and Massa go fourth and fifth.

Ocon is warned of a right-rear puncture, whilst Button warns of heat from the right hand side of his car.

Drama in the pitlane as Perez heads into the pits with smoke coming from the rear of his car. "I don't know if it's the brake discs or exhaust," he admits. He is pushed into his garage as smoke continues to billow from the VJM09.

In all the excitement, Vettel has gone quickest with a 25.193, the German, like his teammate, on softs.

Massa spins at T5 thereby bringing out the yellows.

Verstappen goes seventh with a 27.310, just ahead of his (new) teammate.

"I can't accelerate somehow," says Verstappen, the Dutchman having slowed significantly. However, the problem appears to resolve itself and he picks up speed.

Vettel raises the bar with a 25.060, Rosberg responds but remains 0.154s off the pace.

Alonso, in one of the most heavily updated cars, improves to seventh with a 27.123, albeit 2.2s off Vettel's pace.

Rosberg is the first driver to break the 1:24s barrier, the championship leader banging in a 24.880.

Sainz improves to seventh, but is instantly demoted by former teammate Verstappen who posts 26.962. Ricciardo improves to fifth with a 26.405.

After forty minutes, when the extra set of tyres have to be handed back, the order is: Rosberg, Vettel, Hamilton, Raikkonen, Ricciardo, Bottas, Verstappen, Sainz, Massa and Alonso.

Check out our Friday gallery, here.