Carlos Sainz was quickest and Charles Leclerc completed a Ferrari one-two on Friday as championship leader Max Verstappen struggled in the second practice session for the Singapore Grand Prix.

Sainz was timed under lights at 1min 32.120sec, 0.018sec ahead of Leclerc, as Ferrari dominated in conditions expected to be most similar to those for qualifying on Saturday and for Sunday's night race.

"The car seemed to be in the right window from the very first lap, so we kept focused on fine tuning the set-up," said Sainz.

"I expect the track to improve for tomorrow, so we should have higher grip and then we'll see how much our competitors and ourselves can improve for qualifying."

The Red Bulls have been unstoppable so far in 2023, winning all 14 grands prix, with flying Dutchman Verstappen taking the chequered flag 12 times, including the last 10 races in a row. Sergio Perez has won the other two.

But Verstappen could only finish in eighth place 0.732sec adrift of Sainz with Perez just 0.040sec quicker in seventh.

"Our performance today was unexpected. We never really got the car together," said Verstappen, who is seeking a first victory in Singapore and a record-extending 11th in a row.

"I struggled with the balance, especially, so there are quite a few things to work on. There's quite a gap, the Ferraris are looking fast. Let's see what improvements we can make overnight."

Perez had similar woes, at one point snarling at his race engineer on team radio: "It's just not happening, mate. Every braking zone I feel like I'm going to crash. The rear is stepping out massively."

After the session Perez was still complaining.

"We did expect the Ferrari to be good around here, but we are just too far away," said Perez. "The main thing is to improve the balance because right now we are too far off."

Leclerc said he would not get "carried away" after a perfect Friday when Ferraris topped the timing sheets in both sessions.

"The car looks a bit more competitive than we had expected on a track like this," said Leclerc.

"But we shouldn't get carried away because I think that our competitors are not showing their true pace yet."

George Russell was third in the Mercedes, 0.235sec behind Sainz.

"The car is feeling really good around the circuit," said Russell. "We will do our usual work overnight and hopefully find some improvements heading into Saturday."

Fernando Alonso was fourth in the Aston Martin ahead of Lewis Hamilton's Mercedes with Lando Norris sixth fastest in his McLaren.

Hamilton was buzzing after finishing ahead of the Red Bulls.

"It's been a great day here in Singapore," said the seven-time world champion.

"It was nice to finish a Friday feeling so positive. I think we've got a good platform to build off for the rest of the weekend. It's the best I've felt from a Friday this year." (AFP)