The Mercedes cars of Valtteri Bottas and Lewis Hamilton set the pace in Friday's first practice of the Mexican Grand Prix.
Bottas ran quickest at the Autodromo Hermanos Rodriguez with a lap of 1 minute, 17.824 seconds.
Hamilton was 0.466 seconds behind, with Red Bull's Max Verstappen running third.
Hamilton won in Mexico City last year and is chasing a fourth career season championship.
He can win it Sunday if he finishes fifth or better. Bottas has two wins this season but has missed the podium the last three races.
Hamilton has a 66-point lead over Ferrari's Sebastian Vettel with three races left.
Vettel ran fifth in the morning practice. His session included a drive into the grass at the end of the track's long straight into the first turn.
The turn has new curbs that will require drivers who leave the track to take a slower route to return.
