Ahead of today's second practice session the air temperature is 30 degrees C, while the track temperature is 37 degrees. Humidity is 73%.
As a reminder of the upgrades, Red Bull has a new Floor Edge and Rear Wing Endplate, while Ferrari has a new Front Wing and Mercedes a new Front Corner.
Alpine has a new Sidepod Inlet, Cooling Louvres and Beam Wing, while McLaren has a new Front Wing Endplate, Sidepod Inlet, Halo, Floor Body, Coke/Engine Cover, Rear Corner, Rear Suspension, Rear Wing Endplate and Beam Wing, all of which are only available to Norris this weekend.
Alfa Romeo has new Floor Fences, Diffuser, Rear Corner and Front Wing, while Aston Martin has a new Rear Corner and Williams a new Front Wing.
Like McLaren, AlphaTauri has brought a raft of new parts including a new Floor Body, Floor Edge, Diffuser, Sidepod Inlet, Coke/Engine Cover and Rear Suspension.
The upgrades certainly appeared to work for Norris, while Tsunoda and, to a lesser extent, Bottas appeared to benefit from theirs.
This morning's session was interrupted by lizards - yes, you read that right, lizards - on no less than three occasions, so it is to be hoped that as night falls they will be safely tucked up in their lizard beds.
Leclerc led a Ferrari 1-2 earlier, while Verstappen, Norris, the Mercedes pair and Perez were all there or thereabouts.
It is approaching 21:00, the floodlights have long since sprung into action, in background the city-state sparkles.
The lights go green and Sargeant leads the way, followed by Lawson, Russell, Hulkenberg, Stroll and Bottas.
While Verstappen ran the modified floor in the earlier session, Perez has it this time around. However, with only two of the new floors available the drivers have been instructed not to damage them.
Sargeant posts a 36.897 but Lawson responds with a 35.516 and Russell a 35.424.
No sooner has Leclerc posted a 34.500 then Sainz responds with a 34.150.
Almost everyone is on mediums, though a few, including Norris, are on hards.
Sargeant improves to sixth with a 34.924 as Stroll goes third (34.727).
Sainz improves with a 33.303 as Alonso goes third (33.964), as Albon complains that he lost a lot of power in the final corner. He is told to pit.
Alonso improves to second with a 33.789, but remains 0.486s off Sainz' pace.
Hamilton posts a 34.061 to go fifth as Stroll brushes the wall at Turn 15.
Verstappen is complaining about a lack of rear grip, the world champion is currently ninth 0.988s off the pace.
In the Williams garage Albon is out of his car, and his mechanics get to work on what is believed to be a power unit issue.
A 32.974 sees Leclerc go top.
"****, I'm boxing," declares Verstappen.
With 35 minutes remaining, the majority of drivers switch to the softs.
On the red-banded rubber Sainz improves to 32.120 and Leclerc 32.138. Alonso goes third, ahead of Norris, Bottas, Lawson and Stroll.
As Hamilton goes third, Williams confirms a power unit issue with Albon's car, admitting that the youngster might not be going out again.
Verstappen can only manage sixth, the Dutchman posting a 32.852.
Hulkenberg improves to ninth (33.162), while Norris improves to fifth (32.711).
Red Bull is clearly struggling here, While Verstappen is seventh, teammate Perez is eighth, both over 0.7s off the pace.
"The rears are stepping out massively," complains Perez, "It's just not coming mate, every corner under braking I feel I'm going to crash."
Elsewhere, Sainz complains about traffic.
Perez improves to seventh but remains 0.692s off the pace.
Adding to Red Bull's problem is the fact that its issues are not restricted to one compound it is across the entire range.
The soft runs over, attention switches to Sunday as drivers switch to the mediums.
Ocon is another to have a close encounter with the walls.
The session ends. Sainz is quickest, ahead of Leclerc, Russell, Alonso, Hamilton, Norris, Perez, Verstappen, Magnussen and Bottas.
Hulkenberg is eleventh, ahead of Lawson, Ocon, Stroll, Piastri, Tsunoda, Zhou, Gasly, Sargeant and Albon.
Ferrari will certainly go into this good night feeling quietly confident, as will Mercedes, Norris and Alonso, but Red Bull has a lot of work to do.
Check out our Friday gallery from Marina Bay here.
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