Lewis Hamilton set the pace ahead of Valtteri Bottas in the opening practice for the Spanish GP, a session that saw Fernando Alonso break down on his way into Turn 3.
Formula 1's development war began in earnest at the Circuit de Catalunya on Friday morning as the drivers took to the track in their updated cars, some featuring more upgrades than others.
— Mercedes-AMG F1 (@MercedesAMGF1) May 12, 2017
However, it was another day and another problem for McLaren-Honda as Alonso broke down on his very first lap of the weekend – and did so at the entrance to Turn 3.
His wheels locked up, forcing him into a spin. "Engine problem," he reported before climbing out and calling it quits on FP1.
— Formula 1 (@F1) May 12, 2017
Sebastian Vettel also had an early end to his day as, on his fifth lap of the morning, he reported an "issue with the gearbox, something is broken." He stopped just after the pit lane exit, which meant the marshals could push him back and he was almost immediately into the Ferrari garage.
Ferrari later told reporters that it was a broken rear wheel and not a gearbox issue and Vettel was back running with 35 minutes remaining.
Mercedes, running their updated W08, did not have similar problems.
Lewis Hamilton and Valtteri Bottas led the way on the hard tyres in the opening 40 minutes having traded blows at the top.
Hamilton was quickest with a 1:23.531, 0.083s up on Bottas. Kimi Raikkonen in third place was 0.835s down.
Max Verstappen, who didn't set a time on the hard tyres, went fastest on the medium tyres with a 1:22.706, purple in the second and third sectors.
The Red Bull racer was dropped as Vettel, then Bottas and then Hamilton went quickest.
The Birt finished FP1 with a fastest time of 1:21.521, 0.029s up on Bottas. Raikkonen was third, 0.935s down, while Vettel dropped to fourth.
Verstappen was fifth ahead of Daniel Ricciardo, Kevin Magnussen, Romain Grosjean and Nico Hulkenberg while Carlos Sainz completed the top ten.
Magnussen's session ended seven minutes early as he lost it at Turn 4. He tried to work his way back onto the circuit using the grass around the gravel but eventually parked it.
Sergey Sirotkin, replacing Jolyon Palmer for FP1, completed just 10 laps before the Renault RS17 was back in the garage with a water leak.
1 Lewis Hamilton Mercedes 1:21.521
2 Valtteri Bottas Mercedes 1:21.550 0.029
3 Kimi Raikkonen Ferrari 1:22.456 0.935
4 Sebastian Vettel Ferrari 1:22.600 1.079
5 Max Verstappen Red Bull 1:22.706 1.185
6 Daniel Ricciardo Red Bull 1:23.084 1.563
7 Kevin Magnussen Haas 1:23.670 2.149
8 Romain Grosjean Haas 1:23.758 2.237
9 Nico Hulkenberg Renault Sport 1:23.993 2.472
10 Carlos Sainz Toro Rosso 1:24.004 2.483
11 Sergio Perez Force India 1:24.188 2.667
12 Esteban Ocon Force India 1:24.324 2.803
13 Stoffel Vandoorne McLaren 1:24.400 2.879
14 Felipe Massa Williams 1:24.618 3.097
15 Daniil Kvyat Toro Rosso 1:24.642 3.121
16 Marcus Ericsson Sauber 1:24.966 3.445
17 Pascal Wehrlein Sauber 1:25.182 3.661
18 Lance Stroll Williams 1:25.919 4.398
19 Sergey Sirotkin Renault Sport 1:26.293 4.772
20 Fernando Alonso McLaren No time
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