Carlos Sainz upheld Ferrari's from in Saturday's final practice at Marina Bay, the Spaniard edging Mercedes' George Russell by just 0.069s.
The session left fans with the thrilling prospect of a Ferrari-Mercedes battle in qualifying, with McLaren's Lando Norris lurking just behind.
Max Verstappen in fourth position confirmed that the Dutchman and Red Bull have their work cut out to maintain their winning momentum in Singapore.
The final dress rehearsal ahead of qualifying kicked off under warm conditions – hotter than they will be this evening for quali – with the air temperature at 31°C while track temps sat at 38.9 °C.
While the field opted at the outset for a blend of soft and medium tyres, Sainz, running on the latter, immediately picked up where he left off on Friday, but the Spaniard's early flyer was swiftly beaten by Verstappen.
The two drivers continued to trade fastest laps as the track quickly improved. The soft-shod Mercedes of Russell briefly went top but Sainz reclaimed his favourite spot, lowering the benchmark to 1m33.195s.
On a track that takes no prisoners, AlphaTauri rookie Liam Lawson was lucky to enjoy an inconsequential spin at Turn 3, save for a set of flat-spotted tyres, but it was a close call for the Kiwi.
Up ahead, Russell went fastest again with Hamilton slotting into second to make it a Mercedes 1-2, but the Brackley squad's cars were still the only ones among the front-runners fitted with the softs.
With 20 minutes to go Russell pressed on with a 1m32.364 that kept Hamilton at bay by 0.741s.
However, as the soft tyre became the norm rather than the exception for Mercedes' rivals, Russell was knocked off his perch by Norris, while his McLaren teammate Oscar Piastri also joined the top-five.
But Sainz once again reclaimed the top spot. Meanwhile, a frustrated Verstappen radioed in to signal his discontent with his RB19's upshifts, which he deemed "unacceptable".
A final effort in the session by Russell pushed the Briton up to second, 0.069s off Sainz. Ferrari thus had the last word over Mercedes, with Norris concluding the session third.
Red Bull appeared to definitely be on the back foot at Marina Bay, with Verstappen clocking in fourth while Perez was eighth.
Leclerc, Hamilton and Piastri filled positions fifth to seventh while Nico Hulkenberg in P9 confirmed Haas' strong form in Singapore.
AlphaTauri's Yuki Tsunoda closed out the top ten but Lawson was only a few tenths off his teammate's best.
Alpine appeared to make little progress compared to Friday with Esteban Ocon and Pierre Gasly, respectively in P12 and P15, while Aston Martin's pace was also subdued with Alonso's best only worth P13, just one spot ahead to Lance Stroll.
All signs point to a Ferrari-Mercedes battle for pole, with McLaren just behind. It's a refreshing prospect but one can't dismiss a turnaround by Red Bull and Verstappen.
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