Mercedes's Nico Rosberg has clocked the fastest time in the first practice of the day at Spa Francorchamps ahead of this Sunday's Belgian Grand Prix.

The drivers returned to work after a four-week summer break to the news that Max Verstappen will make his Formula 1 debut at the age of 17 for Toro Rosso next season.

While the news of the Dutchman's impending arrival has dominated the build-up to Formula 1's return this season, on the track, Rosberg and Lewis Hamilton's rivalry is set to continue.

The pair secured their fifth one-two of the season with Rosberg coming out on top in a time of 1:51.577 after completing 25 laps, while Hamilton clinched a best time of 1:51.674 after 24 laps.

Ferrari's Fernando Alonso finished third on the timesheet at Spa, while Jenson Button of McLaren took fourth spot and Red Bull duo Daniel Ricciardo and Sebastian Vettel finished ninth and 11th quickest respectively.

Full practice standings:

1. Nico Rosberg (Mercedes)
2. Lewis Hamilton (Mercedes)
3. Fernando Alonso (Ferrari)
4. Jenson Button (McLaren)
5. Kimi Raikkonen (Ferrari)
6. Sergio Perez (Force India)
7. Kevin Magnussen (McLaren)
8. Nico Hulkenberg (Force India)
9. Daniel Ricciardo (Red Bull)
10. Valtteri Bottas (Williams)
11. Sebastian Vettel (Red Bull)
12. Daniil Kvyat (Toro Rosso)
13. Romain Gorsjean (Lotus)
14. Adrian Sutil (Sauber)
15. Felipe Massa (Williams)
16. Jean-Eric Vergne (Toro Rosso)
17. Giedo Van der Garde (Sauber)
18. Pastor Maldonado (Lotus)
19. Jules Bianchi (Marussia)
20. Alexander Rossi (Marussia)
21. Andre Lotterer (Caterham)
22. Marcus Ericsson (Caterham)