Ahead of today's opening session the air temperature is 25 degrees C, whilst the track temperature is 34 degrees. It is bright, sunny and fairly warm.

There are two reserve drivers on duty this morning, Charles Leclerc replaced Esteban Gutierrez at Haas, while Sergey Sirotkin takes over Kevin Magnussen's Renault.

As luck would have it, this is Magnussen's penultimate race with the French team and is heavily linked with Haas, Gutierrez having confirmed overnight that he is leaving.

As in previous races a number of teams are running the Halo device this morning, Manor using it for the first time. Sauber and Force India are also trying the controversial devices for which there is no timescale in terms of its introduction.

Bottas leads the way, the Finn followed by Vettel, Grosjean, Ocon and Raikkonen.

As more drivers head out there is a balanced mixture of soft and medium while only Bottas sports the hards.

As is ever the case the drivers complete one - sometimes two - laps before heading back to the pits.

Hamilton heads out wearing an Ayrton Senna tribute helmet. The Briton's car is fitted with a very large aero sensor rake at the back of the car as Mercedes looks ahead to next season,

Eight minutes in and the track falls silent, everyone having made an appearance.

"FP1 is go," says Pirelli. "We're here with hard, medium and soft compounds (given increased aerodynamic and performance loads compared to previous years)."

As the Halo is removed from Grosjean's Haas - after just one lap - Pirelli tweets: "Expect usual FP1 test programme. We've seen all three compounds on track already."

Wehrlein, who has been snubbed by Force India in favour of teammate Ocon, posts the first time of the weekend, crossing the line at 1:17.977.

The German is soon joined on track and on the timesheets with Bottas posting 13.977 and Button 14.252.

Intriguingly, Hamilton posts 13.447 to go quickest, his car still sporting that massive aero rake. The mind boggles. The Briton is told to stay off the kerbs, particularly at T2.

Wehrlein complains about his brakes, the German saying that they pull to the left under braking.

Hamilton improves to 13.182 as Massa, in his final Brazilian Grand Prix and his car sporting Massa decals as opposed to Martini, goes third (13.860).

Rosberg, sporting 2017 components front and rear, goes second with a 13.623, 0.441s off his teammate's pace.

Raikkonen improves to fifth (14.014) and Vettel eighth (14.352) ass Ricciardo remains the only driver yet to post a time.

Rosberg improves to within 0.005s of his teammate.

Sirotkin enters the pits very, very slowly, his Renault appearing to have a power issue. "Recharge on," he is told. "Something happened, something happened," he says as mechanics run to his aid.

Ricciardo posts 13.851 to go fourth, behind Hamilton, Rosberg and Bottas.

"I screw up the lap," admits Perez as he posts 14.558.

Verstappen posts 13.722 to leapfrog his Red Bull teammate. A 13.425 subsequently sees the teenage move ahead of Bottas to third only to be demoted when Ricciardo responds with a 13.342.

"The top three have used only the medium tyre in this session so far," reveals Pirelli. "But it's very likely we'll see some rain at some point over the weekend."

Told to pit, Ricciardo is also advised to "attack at pit entry, we do not need these tyres again".

"We're already quicker than last year's FP1 time," adds Pirelli. "For reference, 2015 pole was 1:11.282s. Still some way to go to get there."

After 40 minutes the drivers head back to the pits to hand back a set of tyres.

Oh dear. The cameras pick up on Toto Wolff walking through the paddock in a pair of ripped jeans.

After several minutes of nothing, an engine finally fires up, it is the Honda in the back of Alonso's McLaren. The Spaniard heads down the pitlane.

Sirotkin's session appears to be over, the Renault suffering a fuel pressure issue. Elsewhere, the other reserve driver on duty this morning, Leclerc, performs a practice start. The Monegasque driver subsequently posts 15.391 to go 17th.

Bottas switches to the softs, as does Verstappen, the Dutch youngster going quickest in all three sectors to post an 11.991.

Moments later, Rosberg, also on the softs, posts 12.125, having only been quickest in the final two sectors.

Check out our Friday gallery from Interlagos, here.