Charles Leclerc led the running in the first practice session at the Mexico City Grand Prix on Friday.
The Ferrari driver topped the timesheets 0.659 seconds ahead of title leader Kimi Antonelli, on a weekend the Italian youngster can wrap up the title for Mercedes.
Mercedes reserve Frederik Vesti stepped up and replaced George Russell in the session and crossed the line in third, seven-tenths off the leader's pace.
Leclerc's teammate Lewis Hamilton was fourth, while Ayumu Iwasa, who replaced Max Verstappen in the Red Bull, rounded out the top five.
Antonelli missed Thursday's media duties but returned to practice and is on track to take the drivers' title for the first time. He needs to finish Sunday's race ninth or higher to take the crown.
British driver Freddie Slater made his Formula 1 debut driving for Audi. The 18-year-old finished 21st, but suffered reliability issues which limited his time out on track.
- Lando Norris sends message to F1 drivers unhappy with cars: 'Do a better job'
- Lewis Hamilton on racing into mid-40's: 'Never had anyone like me in 70 years, I'm built differently'
- Sergio Pérez's F1 second act: Red Bull regrets, redemption and a fresh start at Cadillac
Ferrari were the only team to have both drivers in its car, while the rest opted to have a rookie stepping in for one of their drivers.
Alpine's Pierre Gasly finished sixth with Aston Martin's Fernando Alonso in seventh.
Oscar Piastri in the McLaren was eighth, while Leonardo Fornaroli was in Norris' machinery and finished 17th.
Second practice goes green at 10 p.m. GMT / 5 p.m. ET.