Lewis Hamilton described his opening day of running as "solid", as he aims to make small improvements ahead of Saturday's qualifying session.
With the heat and humidity providing the drivers with a major concentration challenge in Singapore, Hamilton states that it is always a "shock" when you return to drive in the Asian country.
"It's been a good day, it's been a hot day," he said. "It's always a shock to the system when you get into the car here. It's so bumpy, it's a long, long lap and it's like a sauna in the car.
"But it was a solid day, we got through our run plan and we're continuing to improve the car, so I was really happy with it."
"I felt much better int he car today than I have for a while, so I hope that stays over the weekend. I think they re-did a few patches of tarmac on the circuit, managing to get the tyres working well.
"If you can get into a groove and rhythm here, it's such a beautiful lap. I've really been enjoying it."
Hamilton added that "nothing is perfect", but that there is nothing troubling missing from the team and its pace.
The five-time world champion says that only "fine" pieces need to be found to fit the puzzle in order to maximise the potential of the car.
"We definitely do have areas that we can improve, nothing is ever perfect," Hamilton admitted. "So now we can go to study areas on the car that we can improve, but areas I can improve, some areas like braking and turning points.
"It's all fine pieces to the puzzle to make it perfect sp I'm looking for that sp[ecial lap that we had last year. We got off to a good start, but still putting it all together tomorrow will be tough.
"The Red Bulls look very, very quick, so I'm excited for the challenge. I was quickest in that session, but they were very close behind us. Whether or not he [Verstappen] had a perfect lap or whether we're more turned up than then, we'll find out later."
Bahrain International Circuit - Winter testing