Oscar Piastri's McLaren teammate and championship rival Lando Norris has set the pace in final practice ahead of qualifying for the Mexican grand prix.
The Briton ended the session 0.345 seconds clear of Ferrari's Lewis Hamilton.
Piastri was almost six tenths adrift in fifth while the third man in the title race, defending champion Max Verstappen, was more than six tenths back in sixth.
Verstappen is the man in form, winning three of the last four races, and is favourite in Mexico City, where he has won five times before.
He trails drivers' championship leader Piastri by 40 points - down from 104 five races ago - and is 26 behind second-placed Norris with 141 points still to fight for.
Verstappen has beaten the McLaren duo in each of the last four races and qualifying sessions and was fastest in practice on Friday.
But Norris surged to the fore on the soft-tyre run on Saturday to deliver a lap of 1.16.633 that nobody could come close to matching.
George Russell was third for Mercedes ahead of Ferrari's Charles Leclerc in fourth to hint at a four-team battle for the front rows of the grid.
Piastri struggled in Austin last weekend, trudging home in fifth, and has been off the pace throughout practice in Mexico.
He ended Friday's running down in 12th and could not deliver the pace of his team-mate in Saturday's final practice before qualifying.
