Red Bull's Max Verstappen headed title contenders Sebastian Vettel and Lewis Hamilton in a tight final practice session at the Singapore Grand Prix.
The Dutchman was 0.072 seconds quicker than Vettel, who was 0.07secs up on Hamilton, setting up a potentially close three-way fight in qualifying.
Verstappen's team-mate Daniel Ricciardo may have been near to the top had he not hit a wall on his final run.
McLaren impressed, with Fernando Alonso and Stoffel Vandoorne fourth and fifth.
The Spaniard and the Belgian were quicker than the second Mercedes and Ferrari, with Finns Valtteri Bottas and Kimi Raikkonen struggling in eighth and ninth places.
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Alonso was just 0.554secs off the pace, underlining the reasons behind McLaren's decision to ditch Honda as their engine supplier and switch to Renault next year.
The McLarens remain slow in the speed traps, but engine power is less important in overall lap time at Singapore than at any track other Monaco and Hungary so the quality of the McLaren chassis and drivers can shine.
At the front, Red Bull continued their strong pace from Friday, but the closeness of Vettel and Hamilton suggests that when the top two teams turn up their engines in qualifying they may sneak ahead.
Renault does not have the same extra power boost for the final stages of qualifying and so always tend to lose some ground.
Hamilton's pace will be encouraging for Mercedes, who came to Singapore expecting to struggle compared to Ferrari on a track that does not suit the characteristics of their car.
Ricciardo had been quickest in both sessions on Friday but Verstappen was edging him throughout this session and the Australian brushed a wall at Turn Nine on his final attempt at a fast lap and returned to the pits to check for damage, ending up sixth.
But he can be expected to be in the mix at the front come qualifying.
Renault also look set for a strong showing, with Nico Hulkenberg seventh quickest.
Team-mate Jolyon Palmer, who found out this week he is being dropped for 2018 in favour of Toro Rosso driver Carlos Sainz, was 0.8secs slower and down in 13th place.
Rumours that Renault are trying to find a way to get Sainz into the car for the next race in Malaysia continue to circulate in the paddock, but so far Palmer has insisted he intends to see out his contract to the end of the season.
The session was interrupted for nine minutes to clear up debris left when Sauber's Marcus Ericsson hit the wall at Turn 19. The Swede's rear wing was damaged but he was able to drive the car back to the pits.