German driver Sebastian Vettel of Ferrari prepares during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019. (Photos: Xinhua)

German driver Nico Hulkenberg of Renault competes during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

French driver Charles Leclerc of Ferrari waits in the pit during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

British driver Lewis Hamilton of Mercedes drives out of the pit during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

The car of Mercedes' Finnish driver Valtteri Bottas is reflected in the visor of a teammate as he returns to the pit during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

British driver Lewis Hamilton of Mercedes competes during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

German driver Sebastian Vettel of Ferrari prepares during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

French driver Charles Leclerc of Ferrari drives out of the pit during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

Finnish driver Valtteri Bottas of Mercedes leaves the pit building after the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

Dutch driver Max Verstappen of Red Bull waits in the pit during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

The pit crew of Ferrari perform a change of tires during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

Dutch driver Max Verstappen of Red Bull competes during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.

Finnish driver Valtteri Bottas of Mercedes waits in the pit during the second practice session of the Formula One Singapore Grand Prix held at the Marina Bay Street Circuit in Singapore, on Sept. 20, 2019.