Nico Rosberg dominated the opening practice session for the United States Grand Prix, putting himself over 1.2 seconds clear of the nearest car.
The session was wet from start to finish, but a dry line began to appear in the closing minutes, however it was too late for any dry tyre running.
Rosberg mastered the conditions, putting himself ahead of the two Red Bulls and Carlos Sainz’s Toro Rosso.
Team-mate and championship leader Lewis Hamilton finished down in fifth, 1.7s adrift of Rosberg’s best.
2015 United States Grand Prix Practice Times (FP1):
| # | Driver | Team | Time | Gap | Laps |
| 01 | Nico Rosberg | Mercedes | 1:53.989 | – | 7 |
| 02 | Daniil Kvyat | Red Bull | 1:55.224 | 1.235 | 6 |
| 03 | Daniel Ricciardo | Red Bull | 1:55.592 | 1.603 | 10 |
| 04 | Carlos Sainz | Toro Rosso | 1:55.667 | 1.678 | 8 |
| 05 | Lewis Hamilton | Mercedes | 1:55.693 | 1.704 | 4 |
| 06 | Sebastian Vettel | Ferrari | 1:55.710 | 1.721 | 10 |
| 07 | Max Verstappen | Toro Rosso | 1:55.969 | 1.980 | 7 |
| 08 | Kimi Raikkonen | Ferrari | 1:56.326 | 2.337 | 10 |
| 09 | Fernando Alonso | McLaren | 1:56.839 | 2.850 | 18 |
| 10 | Valtteri Bottas | Williams | 1:56.866 | 2.877 | 15 |
| 11 | Felipe Massa | Williams | 1:57.081 | 3.092 | 13 |
| 12 | Sergio Perez | Force India | 1:57.139 | 3.150 | 4 |
| 13 | Nico Hulkenberg | Force India | 1:57.495 | 3.529 | 20 |
| 14 | Jenson Button | McLaren | 1:57.518 | 3.715 | 4 |
| 15 | Romain Grosjean | Lotus | 1:58.319 | 4.330 | 10 |
| 16 | Raffaele Marciello | Sauber | 1:59.431 | 5.442 | 19 |
| 17 | Marcus Ericsson | Sauber | 1:59.743 | 5.754 | 18 |
| 18 | Alexander Rossi | Marussia | 2:01.154 | 7.165 | 11 |
| 19 | Will Stevens | Marussia | 2:01.907 | 7.918 | 13 |
| 20 | Pastor Maldonado | Lotus | – | – | 1 |
