Lewis Hamilton set the fastest time of FP1 for the Monaco Grand Prix as a loose drain cover caused damage for Nico Rosberg and Jenson Button to end the session early.
Rosberg was 0.101s off Hamilton's time of 1:15.537 when he exited St Devote and ran over a loose drain cover, flicking it out on to the track and in to the path of the following McLaren. Button could not avoid the object which he ran over with his front right wheel, damaging the front wing and causing a puncture.
Rosberg also had a puncture from the incident - which could have been much more serious had the drain cover been flicked up higher in front of Button - and the session was red flagged with four minutes remaining, leaving the two Mercedes drivers top of the times.
Sebastian Vettel was third quickest for Ferrari, 0.419s adrift of Hamilton and over 0.3s clear of the Red Bull pair of Daniel Ricciardo and Max Verstappen. Daniil Kvyat was sixth fastest and just 0.055s slower than the man who replaced him at Red Bull.
The loose drain cover was not the only incident at St Devote, with Felipe Massa crashing early in the session. Massa lost the rear of the Williams at the apex and hit the barrier on the outside of the track, damaging the whole left side of his car quite heavily.
Jolyon Palmer also hit the wall later in the session, sliding wide at Tabac and damaging his right rear suspension. The contact forced Palmer to stop at the Swimming Pool, ending his running with a little over 20 minutes to go.
While a number of drivers ran wide at St Devote, Valtteri Bottas had a major moment in the tunnel late in the session. The Williams driver had the rear of the car step out on him at high speed in the tunnel and just managed to catch it before the car touched the barrier in an excellent display of car control.
Esteban Gutierrez similarly did well to hold on to his car when the rear of his Haas snapped away under braking for the Nouvelle Chicane. However, Gutierrez later had to stop at Portier due to a technical problem.
Mercedes tried the ultrasoft tyre for the first time from the start of the opening practice session, with the majority of teams following suit. The new compound is making its debut in Monaco this weekend.
AS IT HAPPENED: Monaco Grand Prix - FP1
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| Pos | Driver | Team | Time | Laps |
|---|---|---|---|---|
| 01 | Lewis Hamilton | Mercedes | 1:15.537 | 31 |
| 02 | Nico Rosberg | Mercedes | 1:15.638 | 39 |
| 03 | Sebastian Vettel | Ferrari | 1:15.956 | 26 |
| 04 | Daniel Ricciardo | Red Bull | 1:16.308 | 29 |
| 05 | Max Verstappen | Red Bull | 1:16.371 | 30 |
| 06 | Daniil Kvyat | Toro Rosso | 1:16.426 | 37 |
| 07 | Nico Hulkenberg | Force India | 1:16.560 | 34 |
| 08 | Sergio Perez | Force India | 1:16.697 | 28 |
| 09 | Kimi Raikkonen | Ferrari | 1:16.912 | 24 |
| 10 | Carlos Sainz | Toro Rosso | 1:17.130 | 39 |
| 11 | Valtteri Bottas | Williams | 1:17.562 | 44 |
| 12 | Romain Grosjean | Haas | 1:17.599 | 33 |
| 13 | Fernando Alonso | McLaren | 1:17.838 | 27 |
| 14 | Esteban Gutierrez | Haas | 1:17.909 | 25 |
| 15 | Jenson Button | McLaren | 1:17.920 | 26 |
| 16 | Felipe Nasr | Sauber | 1:18.187 | 29 |
| 17 | Kevin Magnussen | Renault | 1:18.274 | 34 |
| 18 | Marcus Ericsson | Sauber | 1:18.301 | 33 |
| 19 | Felipe Massa | Williams | 1:18.746 | 10 |
| 20 | Jolyon Palmer | Renault | 1:18.871 | 22 |
| 21 | Rio Haryanto | Manor | 1:20.528 | 28 |
| 22 | Pascal Wehrlein | Manor | 1:20.868 | 25 |
