They nevertheless ended up second and fourth behind Sainz, splitting Mercedes pair George Russell and Lewis Hamilton, who had topped the day’s earlier FP1 session at the Marina Bay track.
At the start of the only comparably practice session for qualifying and the race given it’s night-time start, Valtteri Bottas was the first driver out of the pits as the early runners toured around on the medium and hard tires.
Bottas established the first place benchmark at 1m45.839s on the mediums, before he was shuffled back by Mercedes pair Russell and then Hamilton, who completed his first flier at 1m44.091s.
Russell remained at the top of the times until the end of the opening 10 minutes, the Briton’s opening run including an off-track moment the turn 11 almost right that leads onto the Anderson bridge at the bottom end of the circuit.
He managed to get his Mercedes stopped, but only just before the barrier before reversing and continuing on his way.
Sainz then took over at the head of the times with a 1m43.710s – also on the medium tires being run by the two Mercedes drivers – before Hamilton edged back ahead with a 1m43.668s a few minutes later.
At the end of the one-hour session’s first third, Sainz moved back to the top of the times with a 1m43.237s that stood as the definitive medium tire time for the next phase.
By this point, it was clear the championship leaders were having an unusual session, with Verstappen and his teammate Sergio Perez, and Leclerc, yet to set a time.
Red Bull was working on both of its cars in its garage, while Ferrari reattached Leclerc’s floor, which meant they ran out of sync with the rest of the pack when they did emerge.
Perez was the first of the trio to do so – immediately heading out to conduct a qualifying simulation run on the softs, which Bottas had just used at this point before the halfway mark to jump up the order to sit second behind Sainz’s best on the mediums .
On it from the off on his flier, Perez had a massive slide exiting the turn 5 long right that feeds onto the track’s first long straight and he lost further time in the final two sectors to end up nearly 1.5s behind the leading time on the hard rubber.
A few minutes later, Sainz completed Ferrari’s first soft-shod run – improving his first place benchmark to 1m42.751s.
This came despite the Spaniard clipping the wall exiting the Turn 19 90-degree right that follows the brief sub-terrain section of track that runs under the grandstand overlooking the short blast between Turns 17 and 18, which Perez and Esteban Ocon also did on their first qualifying simulation laps.
Ocon’s time was good enough to go third at this stage despite the wall strike, with Leclerc at this point finally taking to the track.
He did so on the mediums and completed a long run that featured a series of personal best laps – the first of which came in just 0.1s slower than his teammate’s previous session-leading time on the yellow-walled rubber.
As Leclerc continued to pound around and improve his personal best, Sainz went again on the softs.
With just over 20 minutes remaining he improved the best time to a 1m42.587s, with Leclerc, by this point running in the other Ferrari’s wake, slotting into second 0.295s back on his used mediums.
That demoted Russell to third and Hamilton to fourth – the Silver Arrows pair having completed qualifying simulation runs on the softs that featured rapid opening sectors before they lost time to Sainz as the lap went on.
Perez had two more goes on the softs during the late-FP2 period that usually features the teams giving their drivers the task of conducting high-fuel race-data-gathering exercises.
His second effort barely closed the gap to Sainz but on his third go he matched the Spaniard in the opening sector before losing so much time in sector two he backed off and headed to the pits.
During this action, Verstappen had come out for a brief sighter on the hards before returning to the Red Bull pit for another long stint of set-up adjustments, which meant he languished in 15th heading into the final 15 minutes.
It was clear none of the Dutchman, Perez or Leclerc would be able to conduct the usual late-FP2 high runs and indeed they were switched to qualifying simulation runs for the closing stages, ending up with lap totals of eight, 12 and 13 respectively.
Leclerc went first on the softs and was nearly 0.2s up on Sainz in the first sector before falling back to level with his teammate’s best time after completing the middle third and eventually posted a time that kept him second but 0.208s down.
A short while later with four minutes of the session left on the clock, Verstappen went even better in the first sector to head Sainz by 0.2s.
But he too slid back to level pegging at the end of sector two and then lost so much time in sector three – over 0.3s – his personal best meant he only slotted in fourth behind Russell’s best soft-tyre effort from earlier in the session.
That pushed Hamilton and Ocon back to fifth and sixth in the final order, with Bottas and Fernando Alonso seventh and eighth, as Perez trailed in ninth.
Lance Stroll rounded out the top 10 in a session that, as usual for the tricky street track, featured a raft of lock-ups and dives down escape roads, but no one hit the walls hard enough to cause a stoppage.
The most dramatic moment of proceedings was Pierre Gasly – 14th fastest – having to rapidly leap from his AlphaTauri when being wheeled back into his garage as flames burst from the car’s airbox.
The incident happened with just over 15 minutes of the session to go, with the fire rapidly extinguished just as Gasly was climbing out of his cockpit.
