Red Bull, who have struggled in Singapore for the past couple of seasons, felt they had had a positive day.
Verstappen, the winner of the past two races at Monza and Baku, said: “The car was not too bad, a bit like the last two weekends. There were no major problems.
“Tried a few things, some were good and we just need to try and optimise that a bit more. In general quite satisfied, but definitely need a bit more pace to fight up at the front tomorrow.”
The disrupted session meant drivers did not have time to do their race-simulation runs at the end, so a clear indication of form did not emerge.
Alonso was quick all day in the Aston Martin on a track where the car’s weaknesses are not exposed and where he has always been strong.
But the team would be expected to slip down the field on Saturday.
Alonso said: “Seems little bit better than the previous grands prix. Let’s try to fine-tune the set-up. It’s still not in a happy place, especially on the front axle. Still a little bit too much understeer. Something to work tonight but a good start.
“Since the first lap we were in a comfy place and were able to find the limits quite quickly.
“Let’s see if we can be in Q3 tomorrow and points on Sunday. Both sessions in the top four is probably the best Friday so far but sometimes Friday we run with a different programme or different fuel, and the real test is tomorrow.”
His team-mate Lance Stroll was sixth fastest, 0.345secs off the Spaniard, followed by Haas driver Esteban Ocon, Williams’ Carlos Sainz and the Ferraris of Leclerc and Lewis Hamilton.
Leclerc said his second session had been messy and blamed the pit-lane incident on “a combination of things” and “a bit of confusion”, but he said: “The good thing is the pace is in the car.”
Hamilton added: “It’s generally been a good day. I have enjoyed driving the car.
“Obviously, McLaren are very fast, and getting a clean lap is not easy, but I feel like there’s lots of positives to take from today, lots of learnings and quite happy with the progress we made from session to session.
“We made steps forward today so overnight we probably won’t change much. But see if we can extract a little bit more to get as close as we can to the McLarens.”
