Nico Rosberg has finished ahead of teammate Lewis Hamilton in a first practice session dominated by Mercedes at the Italian Grand Prix.
The German was 0.203s quicker than the man that he trails by nine points in the championship standings, while Kimi Raikkonen finished a second off the pace in third.
Plenty of attention will be on Felipe Massa following his announcement this week that he intends to retire at the end of the year, but he could only finish in 14th in the day's first session.
Meanwhile, the fastest Red Bull driver was Max Verstappen in eighth, with Daniel Ricciardo two places further back on the Autodromo Nazionale Monza course.
1. Nico Rosberg (Mercedes)
2. Lewis Hamilton (Mercedes)
3. Kimi Raikkonen (Ferrari)
4. Sebastian Vettel (Ferrari)
5. Sergio Perez (Force India)
6. Romain Grosjean (Haas)
7. Valtteri Bottas (Williams-Mercedes)
8. Max Verstappen (Red Bull)
9. Esteban Gutierrez (Haas)
10. Daniel Ricciardo (Red Bull)
11. Jenson Button (McLaren)
12. Alfonso Celis (Force India)
13. Fernando Alonso (McLaren)
14. Felipe Massa (Williams)
15. Marcus Ericsson (Sauber)
16. Carlos Sainz (Toro Rosso)
17. Daniil Kvyat (Toro Rosso)
18. Esteban Ocon (Manor)
19. Felipe Nasr (Sauber)
20. Pascal Wehrlein (Manor)
21. Jolyon Palmer (Renault)
22. Kevin Magnussen (Renault)
