Hamilton sets the pace early in damp FP1 in Austin

Lewis Hamilton set the pace in a murky and damp first practice for the United States Grand Prix.

The Mercedes driver's best lap of 1:36.335s was over half a second quicker than Ferrari's Sebastian Vettel at the Circuit of the Americas in Austin, Texas.

United States Grand Prix - Free practice 1 results

The 90-minute session got underway in gloomy and overcast conditions. Early light rain had stopped by the time the track went green, but the Circuit of the Americas was still damp in parts. McLaren's Stoffel Vandoorne and Ferrari's Sebastian Vettel were the first to emerge for shakedown laps.

Conditions meant that intermediates were the consensus choice for the start of the session. Mercedes driver Valtteri Bottas was the first to complete a timed lap, but his team mate Lewis Hamilton soon took over at the top with 1:50.146s.

Red Bull's Max Verstappen quickly raised the stakes. He cut over two seconds off the target time on prototype intermediate rubber he described as "simply lovely." His team mate Daniel Ricciardo went third fastest shortly after going for a spin in turn 9 as a result of running over the wet kerbs.

Toro Rosso's test driver Sean Gelael - sitting in for Daniil Kvyat this morning - had a similar low speed spin in turn 16. He slid on the wet grass and was lucky not to connect with the barrier. Force India's Esteban Ocon was likewise caught out by the wet kerbs, this time spinning at the penultimate corner.

Times began to pick up as conditions started to improve. Vettel soon moved the dial with a lap of 1:45.960s, but his team mate Kimi Raikkonen ran wide and off in turn 19 to demonstrate that it remained tricky out there.

Halfway through the session, Williams' Felipe Massa ventured out on supersofts only to have the same issue as Raikkonen. Even so, it wasn't long before everyone was switching to the slicks for the remainder of first practice.

Ricciardo led the way, quickly going under the 1:40s mark. Verstappen lowered the bar to 1:38.158s, with Hamilton almost immediately meeting the challenge and going almost two seconds faster.

Bottas initially matched Hamilton's efforts before flat-spotting his tyres into turn 1 and suffering severe vibration. It meant an early end to his morning's run. However, many teams had already concluded there was little to learn in the cool and cloudy conditions.

Fernando Alonso was the only driver to not set a timed lap in FP1, although he completed a number of installation laps. A suspected hydraulic leak meant the newly re-signed McLaren driver was left sidelined in the garage.

Making his Formula 1 début at Toro Rosso, Brendon Hartley was 14th fastest. Understandably, the Kiwi spent much of his session sorting out teething problems with his crash helmet and seat position.

Along with Vandoorne and the two Williams, Hartley and Galael were the the only drivers to break into their stocks of ultrasoft tyres during the session.

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