Lewis Hamilton set the pace in the opening practice session for the Brazilian Grand Prix, outpacing Red Bull's Max Verstappen.
The Briton emerged on top with a time of 1:11.895, set on Pirelli's soft rubber, Verstappen finishing just 0.096s behind him.
Nico Rosberg, who could clinch the title this weekend, was third-quickest, over two tenths behind his teammate.
Daniel Ricciardo in the second Red Bull and Valtteri Bottas in the quickest Williams completed the top five.
Sergio Perez and Nico Hulkenberg wound up sixth and seventh ahead of local hero Felipe Massa, in his final Brazilian GP before he retires.
Ferrari drivers Sebastian Vettel and Kimi Raikkonen rounded out the top 10, the duo not running with the soft tyres, using just the mediums as they focused on race work.
Like Ferrari, most teams focused on long runs in the second half of the session, as there is a high chance of rain in FP2.
The FP1 session was off to a very slow start, with drivers completing installations laps before returning to the pits for several minutes.
Three cars sported the Halo device today: the Sauber of Marcus Ericsson, Jolyon Palmer's Renault, and the Haas of Romain Grosjean.
It took over 15 minutes for a driver to register a time before the frontrunners started to complete their first timed laps.
Bottas was the early pace-setter in the Williams, as Hamilton initially focused on slow runs, his Mercedes fitted with several sensors on the rear end.
The Briton then upped the pace and moved to first on medium tyres with a 1:13.447, improving to a 1:13.182 on the following lap of his run.
Rosberg, also on mediums, jumped to second with his first run, just 0.030s behind his teammate.
As the session reached the first 30 minutes, Sergey Sirotkin, replacing Kevin Magnussen at Renault, hit trouble, his car shutting down at the final corner.
The Russian used his momentum to reach the pitlane, but had to be pushed by the mechanics to return to the garage.
He would manage just 10 laps and finish at the bottom of the times, behind Charles Leclerc, driving the Haas instead of Esteban Gutierrez.
Verstappen and minutes later Ricciardo went third quickest, the Australian less than two tenths of a second off Hamilton's pace.
The action stopped as the session neared the halfway point, before Fernando Alonso broke the silence with some 44 minutes left on the clock.
It was Bottas a few minutes later, however, who went quickest in the Williams, the Finn using a new set of soft tyres to outpace Hamilton by 0.028s.
The Williams did not last long on top, as Verstappen went for his first run on softs in the Red Bull, posting a 1:11.991 that put him over a second clear of the rest of the field.
Rosberg's first run on softs produced a time 0.134s slower than Verstappen, putting the German in second ahead of Ricciardo, who also improved thanks to the yellow-marked rubber.
With 30 minutes left, there was drama for Daniil Kvyat as the Russian suffered a puncture to his right rear tyre, needing to crawl back to the pits with a destroyed Pirelli.
Hamilton set a new benchmark with his first run on soft rubber, the Mercedes driver posting a 1:11.895 with some 26 minutes to go.
With three minutes left, Vettel spun off the track during a long run after losing control of his car at Turn 11.
|2||Max Verstappen||Red Bull||TAG||29||1'11.991||0.096||0.096|
|4||Daniel Ricciardo||Red Bull||TAG||27||1'12.371||0.476||0.246|
|6||Sergio Perez||Force India||Mercedes||31||1'13.289||1.394||0.160|
|7||Nico Hulkenberg||Force India||Mercedes||33||1'13.293||1.398||0.004|
|11||Carlos Sainz Jr.||Toro Rosso||Ferrari||22||1'13.711||1.816||0.142|
|12||Daniil Kvyat||Toro Rosso||Ferrari||15||1'14.090||2.195||0.379|