Hamilton leads the first wet track practice of 1.3s

Hamilton beat Valtteri Bottas by 1.3 seconds to comfortably lead a double Mercedes on a rainy circuit of the Americas in Austin.

The Red Bull Max Verstappen duo and Daniel Ricciardo were the closest opponents of Mercedes as Ferrari seemed to be concentrating on longer distances and his title rival, Hamilton, Sebastian Vettel, was fifth and nearly two seconds behind.

Most of the facilities were cordoned off in the first 10 minutes, while the runway was the wettest after heavy morning rain. Nico Hulkenberg was the first to switch to intermediate tires 17 minutes after the start of the session.

It took a little more time for someone to set a time but the Red Bulls ended the wait. Ricciardo led Verstappen on a time of 1m50.642.

Ricciardo lowered the score to 1m49.386s shortly after, before Bottas reached the top spot at the half-hour mark by placing a 1m48.806s in his Mercedes.

Several riders arrived in the standings before the half-way point of the 90-minute session, but there was a runway break at that point to clear gravel at Turn 9.

Charles Leclerc had spun his Sauber at the end of the quick jump sequence at the start of the lap, and had to cross the gravel to meet.

He dropped a lot of pebbles on the track just as he climbed and fell through the turn of Turn 10 until the left-handed bend.

This caused a 10-minute stop while the marshals cleaned the runway.

Hamilton bombarded Bottas' benchmark with just over a third of the remaining session, and his immediate opponents did not improve until the end.

Vettel has never been troubled at the top of the standings, as he and his teammate Kimi Raikkonen led longer runs than their rivals, finishing respectively with 17 and 19 laps. Neither Mercedes nor Red Bull have managed to double their numbers.

However, Vettel managed to overtake Raikkonen in the fifth and finally outclassed the Finn by half a second.

Carlos Sainz finished better for Renault in seventh, while Haas's Romain Grosjean finished eighth ahead of Leclerc's Saubers, who had made a late improvement, and Marcus Ericsson.

Two pilots were driving in FP1 instead of regulars. Lando Norris driving the McLarens of Stoffel Vandoorne and Sean Gelael replacing at Brendon Hartley in Toro Rosso.

Norris finished the 12th session, one place and two tenths behind his teammate Fernando Alonso, while Gelael was the slowest of the 20 starters and 1.4 seconds behind Pierre Gasly in the sister car.