Nico Rosberg set the fastest time of the opening practice session for the United States Grand Prix as teams face wet weather in Austin.
Heavy rain is forecast for Friday and Saturday, with downpours before FP1 ensuring the opening practice session took place on a wet track. Early installation laps took place on full wets before the track improved sufficiently for intermediate tyres, and teams took advantage of the conditions to complete as much running as possible before expected heavier rain in the afternoon.
Rosberg was comfortably faster on the intermediate tyre, setting a best time of 1:53.989 to end the session 1.235s clear of Daniil Kvyat. There was a strong showing for the Renault-powered teams, with Daniel Ricciardo third ahead of Toro Rosso's Carlos Sainz in fourth place.
Lewis Hamilton was fifth fastest - 1.7s slower than his team-mate - but completed only four laps as the top five all ended the session with a lap count in single figures. Sebastian Vettel was sixth for Ferrari and registered ten laps, setting a best time just 0.017s off Hamilton.
While Rosberg set the pace, he did have a brief excursion at Turn 1 in the tricky conditions, before Felipe Massa spun at Turn 9 soon after. After recovering his Williams, the Brazilian radioed in to the team to say he simply lost the rear, before going on to set the 11th fastest time just over 0.2s slower than team-mate Valtteri Bottas in tenth. Bottas did have one concerning moment when he locked up returning to his pit box and slid towards his mechanics who had to jump clear of the car.
Fernando Alonso ended the session immediately ahead of Bottas as McLaren carried out the most running of any team in the opening session. With Alonso running a new specification of power unit, the double world champion was ninth quickest, though ruined any chance to improve on his final lap by running wide at Turn 1 having locked up his front left tyre.
While McLaren registered 38 laps, Sauber was the next busiest team as Marcus Ericsson and Raffaele Marciello completed 37 laps between them. Sauber opted to stick with its planned driver change with Felipe Nasr missing FP1, but Lotus switched around its schedule due to the weather. Romain Grosjean took part in the opening practice session but will hand over to Jolyon Palmer for FP2 for any potential running, with the weather expected to deteriorate.
The forecast is bad news for Grosjean's team-mate Pastor Maldonado, who completed just a single installation lap before complaining of a gearbox problem which confined him for the garage for the rest of the morning.
AS IT HAPPENED: United States Grand Prix FP1
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| Pos | Driver | Team | Time | Laps |
|---|---|---|---|---|
| 01 | Nico Rosberg | Mercedes | 1:53.989 | 7 |
| 02 | Daniil Kvyat | Red Bull | 1:55.224 | 6 |
| 03 | Daniel Ricciardo | Red Bull | 1:55.592 | 10 |
| 04 | Carlos Sainz | Toro Rosso | 1:55.667 | 8 |
| 05 | Lewis Hamilton | Mercedes | 1:55.693 | 4 |
| 06 | Sebastian Vettel | Ferrari | 1:55.710 | 10 |
| 07 | Max Verstappen | Toro Rosso | 1:55.969 | 7 |
| 08 | Kimi Raikkonen | Ferrari | 1:56.326 | 10 |
| 09 | Fernando Alonso | McLaren | 1:56.839 | 18 |
| 10 | Valtteri Bottas | Williams | 1:56.866 | 15 |
| 11 | Felipe Massa | Williams | 1:57.081 | 13 |
| 12 | Sergio Perez | Force India | 1:57.139 | 4 |
| 13 | Jenson Button | McLaren | 1:57.495 | 20 |
| 14 | Nico Hulkenberg | Force India | 1:57.518 | 4 |
| 15 | Romain Grosjean | Lotus | 1:58.319 | 10 |
| 16 | Raffaele Marciello | Sauber | 1:59.431 | 19 |
| 17 | Marcus Ericsson | Sauber | 1:59.743 | 18 |
| 18 | Alexander Rossi | Manor | 2:01.154 | 11 |
| 19 | Will Stevens | Manor | 2:01.907 | 13 |
| 20 | Pastor Maldonado | Lotus | 1 |
