Red Bull are on course to spring a surprise in Singapore after Daniil Kvyat ended the second practice session on top of the timesheets for the first time in his career.
Lewis Hamilton, aiming to join his idol Ayrton Senna with 41 career wins, was a distant fourth for Mercedes while his team-mate Nico Rosberg could manage only seventh.
Red Bull had been optimistic that the low-speed nature of the Marina Bay Street Circuit would suit their cars and Kvyat’s best lap of one minute and 46.142 seconds saw the Russian end the night session leading the way.
Ferrari’s Kimi Raikkonen was just 0.039 seconds adrift of Kvyat, with Daniel Ricciardo, in the sister Red Bull, in third place.
Rosberg had topped the opening session ahead of Hamilton, but the Mercedes pair were off the pace as the day’s play drew to a close.
Sebastian Vettel, a three-time winner in Singapore as a Red Bull driver, was fifth fastest for Ferrari with the Force India of Sergio Perez sixth in the standings.
Mercedes are bidding for their 24th consecutive pole position this weekend which would draw them level with the record set by Williams across the 1992/1993 seasons.
Hamilton, who has claimed 11 poles from 12 grands prix this term, is also on a run of 20 front-row starts, but, on this evidence at least, both streaks appear to be under threat.
Hamilton was joined by the American rapper Pharrell Williams, who will perform here later on Friday, but neither the world champion nor his Mercedes team for that matter, will be happy with their progress under the lights on Friday.
“We are not happy with the performance today,” said Mercedes motorsport boss Toto Wolff.
“We have not really made the tyre work the way we should – on the one-lap performances or the long runs either. We have seen some spectacular laps from the Red Bull so we need to get our heads together and assess what is happening.”
For Red Bull – whose team principal Christian Horner claimed the British based outfit’s participation next season is under threat amid their continued fall-out with engine supplier Renault – it was a throwback to their glory era.
The team, a winner of four consecutive driver and constructors’ titles between 2010 and 2013, have failed to triumph at a race in over a year and have finished on the podium only twice this season. But they will be buoyed by their performance which marked the first time they have topped a dry practice session since the switch to V6 power units at the start of 2014.
McLaren were another team who were expecting to improve on their recent woeful showings and Fernando Alonso finished the session in eighth place within a second of Kvyat.
His team-mate Jenson Button, who expects his future to be sorted by the end of the month, was further back in 14th.
British team Manor endured a troubled evening. Firstly, Alexander Rossi binned his car at turn 18 in the opening session sustaining significant damage to the right-hand side of his Manor. Then, Will Stevens lost control of his car at turn 11.
Rossi, on his grand prix bow, emerged late in the day to complete nine laps, but the American was over 10 seconds slower than the pace-setting Red Bull of Kvyat.