Charles Leclerc set the pace in both practice sessions on Friday at the Mexico City Grand Prix.
The Ferrari driver's best lap of 1:17.827 in the second session put him 0.103 seconds clear of McLaren's Lando Norris, two days before Kimi Antonelli could be crowned world champion.
A clean sweep for Leclerc
Leclerc topped first practice with a 1:18.128, 0.659 seconds ahead of Antonelli's Mercedes. Ten rookies took part in that session, standing in for regular drivers.
He went quicker in the second session despite two aborted laps: he ran wide on one flying lap and locked up into turn one on another.
George Russell was third for Mercedes, 0.003 seconds behind Norris. Antonelli was fourth, with Max Verstappen fifth for Red Bull and his team-mate Isack Hadjar sixth. Oscar Piastri was tenth in the second McLaren.
Hamilton stops, Verstappen collides
Lewis Hamilton's session was cut short when his Ferrari lost power on the main straight and he pulled off the track.
Earlier, Verstappen and Racing Bulls' Liam Lawson went wheel to wheel through the stadium section and made contact. The collision scattered debris from the Red Bull, and the session was stopped with a red flag while it was cleared.
Verstappen returned to the track in his damaged car.
What happens next
Antonelli needs two points on Sunday to become Formula 1's youngest world champion.
Final practice starts at 11:00pm on Saturday 31 October in India, and qualifying at 2:30am on Sunday 1 November. The race starts at 1:30am on Monday 2 November, India time.
Race it on Late Brake
Mexico City is not one of Late Brake's circuits, but the next round is. Interlagos is one of six real circuits in the free browser game: set a lap, race your own ghost and see if you can reach the gold medal time before the season heads to Brazil.
Sources: Autosport FP1, Autosport FP2, The Race FP1, The Race FP2, BBC Sport