Lewis Hamilton has topped the timesheets in final practice for Sunday's United States Grand Prix and could have already secured pole position.

Heavy rain is forecast at the Circuit of the Americas and the session was also in doubt due to the adverse weather, caused by tropical storm Patricia.

However, Hamilton became the only man to break the two-minute barrier at the rain-soaked track, finishing 0.863 seconds ahead of the fastest time from Sebastian Vettel, who will have a 10-place grid penalty for using more engines that permitted during the season.

Qualifying could be moved to Sunday if conditions worsen, but if race officials decide to use times recorded in FP3 then the Briton will start from first, with Nico Hulkenberg also on the front row of the grid.

Hamilton will be crowned world champion for the third time, if he wins in Texas and Vettel fails to finish second.

Full standings:

1. Lewis Hamilton
2. Sebastian Vettel
3. Nico Hulkenberg
4. Valtteri Bottas
5. Carlos Sainz Jr
6. Daniil Kvyat
7. Kimi Raikkonen
8. Daniel Ricciardo
9. Nico Rosberg
10. Felipe Massa
11. Sergio Perez
12. Romain Grosjean
13. Pastor Maldonado
14. Fernando Alonso
15. Marcus Ericsson
16. Jenson Button
17. Will Stevens
18. Alexander Rossi
19. Felipe Nasr
20. Max Verstappen