Lewis Hamilton started the Brazilian GP weekend as he'll hope to continue as he seized the early initiative in Practice One, with Nico Rosberg only third.
Max Verstappen was second quickest, and Rosberg will be hoping the Red Bulls aren't going to make his push for a maiden world title even trickier this weekend.
Surprisingly, less than a tenth of a second separated Hamilton and Verstappen at the top of the standings, despite the advantage the Mercedes power unit has on the long drag up the hill in the final sector.
Verstappen did benefit from a tow from McLaren's Fernando Alonso in sector three, but being three tenths quicker than team-mate Daniel Ricciardo underlined how impressive the Dutchman's lap was.
The fight for fourth in the Constructors' Championship also looks set to be feisty this weekend, with less than two tenths covering the four Force India and Williams cars.
Ferrari looked off the pace and finished the session a disappointing ninth and 10th with Sebastian Vettel and Kimi Raikkonen, respectively. A spin mid-corner in the closing stages of the session underlined the struggles of the Scuderia.
GP3 championship Charles Leclerc made his first F1 appearance since Hockenheim in July for Haas in place of the departing Esteban Gutierrez. The Monegasque driver finished the session in 21st, around eight tenths slower than Romain Grosjean.
The other non-race driver in the session was Sergey Sirotkin, who suffered a fuel pressure problem in the Renault and was slowest in the session.
With the weather forecast unsettled to say the least for the remainder of the practice sessions, the 90 minutes of running may prove pivotal in establishing setups this weekend.
Practice Two gets underway at 4pm GMT, and you can see it live on Sky Sports F1, or follow the session across Sky Sports' digital platforms.
Practice One timesheet
1. Lewis Hamilton, Mercedes, 1:11.895
2. Max Verstappen, Red Bull, 1:11.991
3. Nico Rosberg, Mercedes, 1:12.125
4. Daniel Ricciardo, Red Bull, 1:12.371
5. Valtteri Bottas, Williams, 1:13.129
6. Sergio Perez, Force India, 1:13.289
7. Nico Hulkenberg, Force India, 1:13.293
8. Felipe Massa, Williams, 1:13.318
9. Sebastian Vettel, Ferrari, 1:13.567
10. Kimi Raikkonen, Ferrari, 1:13.569
11. Carlos Sainz, Toro Rosso, 1:13.711
12. Daniil Kvyat, Toro Rosso, 1:14.090
13. Jenson Button, McLaren, 1:14.252
14. Fernando Alonso, McLaren, 1:14.296
15. Romain Grosjean, Haas, 1:14.507
16. Felipe Nasr, Sauber, 1:14.631
17. Marcus Ericsson, Sauber, 1:14.654
18. Esteban Ocon, Manor, 1:14.827
19. Jolyon Palmer, Renault, 1:14.908
20. Pascal Wehrlein, Manor, 1:14.948
21. Charles Leclerc, Haas, 1:15.391
22. Sergey Sirotkin, Renault, 1:15.800
Can Nico Rosberg clinch the title at Interlagos? Watch the Brazilian GP live on Sky Sports F1 on Sunday, the race begins at 4pm; Watch the whole race weekend with a NOW TV week pass - £10.99, no contract