Sainz, who will start third in the sprint today behind Dutchman Max Verstappen in Red Bull and Leclerc, set the fastest lap at Red Bull, which was one minute 08.610 seconds.
Leclerc finished second with 0.050 seconds, while Verstappen finished third with 0.168 seconds.
Spaniard Fernando Alonso, driver of the Alpine Kings for Renault, and his French colleague Esteban Ocon finished fourth and fifth, respectively, ahead of Mexican Sergio Perez, who finished sixth in Red Bull.
Perez will start today’s sprint from 13th after his last lap time was canceled for crossing the circuit limits.
The Mercedes team returned to the track and competition again after its British drivers Lewis Hamilton and George Russell suffered two accidents during qualifying on Friday, which required major repairs to both cars.
Russell set the seventh fastest time of the day, while Hamilton finished ninth in the round.
Russell will start the sprint from fourth, while seven-times world champion Hamilton will start from ninth.
After the first 10 races of the 22-race season, reigning champion Verstappen is at the top of the drivers’ list, 34 points ahead of his teammate Perez, who is in second place, and 43 points ahead of Leclerc, third in the list.
Verstappen is seeking to return to the top of the podium after Sainz’s victory in the British Grand Prix last week halted Red Bull’s six-race winning streak.