Lewis Hamilton edged out Max Verstappen in second practice under the floodlights at the Marina Bay circuit in Singapore.
Hamilton posted a 1:38.773 to finish a tenth ahead of Verstappen, who had topped the first practice session earlier.
The dynamic duo were well clear of the rest as Sebastian Vettel, in P3, was the only driver to finish within a second of the World Championship leader.
Valtteri Bottas was 1.121 seconds off the pace in P4, while Alex Albon recovered from an early barrier bash to finish P5. Charles Leclerc completed the top six.
Second practice offered the first fully representative session of the weekend as preparations ramp up for qualifying and race night on Sunday.
Bottas was ready to go again after his smash into barriers during FP1, but Leclerc was forced to wait (im)patiently in the garage as Ferrari continued to work on his car following his earlier gearbox issue.
Just as Leclerc re-emerged from the garage with just over an hour left on the clock, Albon was heading back in minus a front wing after locking up and running on at Turn 10, bopping the barrier in the process.
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Following the first 30 minutes, none of the top three teams had slapped on the quickest soft tyres with Hamilton topping the timesheet with a 1:39.991 on the mediums; Verstappen (hards), Leclerc (mediums) were both seven tenths off the early pace.
Bottas was a further tenth back on the mediums as he kept a very close eye on those biting barriers.
Then the ante was upped significantly as the qualifying simulations got underway. Hamilton lowered the benchmark to a 1:38.773 on his hot lap attempt, with Verstappen negotiating traffic problems to be a tenth behind.
Vettel was forced to abort his first two hot lap attempts due to traffic issues as well.
On Vettel’s third attempt, he could only improve to be within 1.3 seconds of Hamilton’s then session best. Leclerc only a tenth quicker than his team-mate in P5.
Bottas and Albon were also a second off the pace in P3 and P4 respectively.
Hamilton fell 0.045 seconds short of matching his first qualy sim attempt, while Vettel did manage to hop up to P3 but still eight tenths behind.
Elsewhere, Sergio Perez and Kevin Magnussen were tripping over each other with track space proving very hard to come by under the night lights. The stewards noted the incident.
For the final 30 minutes of FP2, the focus turned to some more race simulation programmes.
Bar Pierre Gasly briefly annoying Hamilton, the programmes passed without incident and the average lap data showed that Mercedes, as expected, are setting the standard in Singapore.
1 Lewis Hamilton Mercedes 1:38.773 28
2 Max Verstappen Red Bull 0.184s 27
3 Sebastian Vettel Ferrari 0.818s 29
4 Valtteri Bottas Mercedes 1.121s 28
5 Alex Albon Red Bull 1.170s 28
6 Charles Leclerc Ferrari 1.245s 28
7 Carlos Sainz McLaren 1.372s 31
8 Nico Hulkenberg Renault 1.551s 30
9 Lando Norris McLaren 1.588s 33
10 Pierre Gasly Toro Rosso 1.864s 30
11 Daniil Kvyat Toro Rosso 1.940s 30
12 Daniel Ricciardo Renault 2.038s 28
13 Sergio Perez Racing Point 2.102s 27
14 Antonio Giovinazzi Alfa Romeo Racing 2.355s 33
15 Lance Stroll Racing Point 2.355s 29
16 Kimi Raikkonen Alfa Romeo Racing 2.459s 26
17 Romain Grosjean Haas 2.619s 26
18 George Russell Williams 2.672s 33
19 Kevin Magnussen Haas 2.791s 28
20 Robert Kubica Williams 3.404s 33
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