The Briton needs to score eight points more than Ferrari rival and fellow-four times champion Sebastian Vettel on Sunday and a third successive Mercedes one-two finish would do just that.
Hamilton, who has won six of the last seven races and is chasing a fifth victory in a row, made an immediate statement of intent with a quickest lap of one minute 47.502, a hefty 1.304 quicker than team mate Valtteri Bottas.
United States Grand Prix
Hamilton fastest again as Austin rain continues
19/10/2018 AT 21:16

Lewis Hamilton of Great Britain and Mercedes GP prepares to drive in the garage during practice for the United States Formula One Grand Prix at Circuit of The Americas on October 19, 2018 in Austin, United States.

Image credit: Getty Images

Vettel was fifth on the timesheets with a 1:49.489, nearly two seconds off the pace, and behind the Red Bulls of Max Verstappen and Daniel Ricciardo.
Ferrari's Kimi Raikkonen was sixth fastest.
Hamilton won his third championship at the Texan track in 2015 and has been almost unbeatable in Austin, winning five of the six races there since Texas first appeared on the calendar in 2012.

Lewis Hamilton of Great Britain and Mercedes GP talks to the media in the Paddock during previews ahead of the United States Formula One Grand Prix at Circuit of The Americas on October 18, 2018 in Austin, United States.

Image credit: Getty Images

With the rain coming down steadily overnight, but easing slightly before the day's action started, Friday's times were comparatively slow and Hamilton took his time before venturing out on track.
The session was briefly red flagged with 48 minutes remaining after Sauber's Charles Leclerc spun at turn eight and went off, scattering gravel across the track.
McLaren gave 18-year-old Briton Lando Norris, who will race for them next season, an outing in Stoffel Vandoorne's car and he was 12th fastest with double world champion team mate Fernando Alonso 11th.
United States Grand Prix
'Stupid idiot!' - Title rivals Hamilton and Verstappen clash
19 HOURS AGO
United States Grand Prix
Bottas fastest in FP1, Hamilton second as Mercedes clear of rivals
YESTERDAY AT 17:58