Red Bull's Daniil Kvyat top in Singapore, Lewis Hamilton fourth
|Singapore Grand Prix on the BBC|
|Venue: Marina Bay Circuit Date: 18-20 September|
|Coverage: Highlights on BBC TV, coverage on BBC Radio 5 live and sports extra, online, mobile, the BBC Sport app and Connected TV|
Lewis Hamilton was only fourth fastest in second practice at the Singapore Grand Prix as Red Bull's Daniil Kvyat set the pace.
Both Mercedes, so dominant in 2015, had a low-key session, as Hamilton's team-mate Nico Rosberg was seventh.
Ferrari's Kimi Raikkonen was second fastest ahead of Kvyat's team-mate Daniel Ricciardo as the top three drivers were covered by only 0.114secs.
Hamilton was 0.337secs off the pace, ahead of Ferrari's Sebastian Vettel.
Force India's Sergio Perez was sixth, with McLaren's Fernando Alonso an impressive eighth behind Rosberg.
Red Bulls charging
Red Bull had long targeted this weekend for a strong result, the tight and twisty nature of the circuit favouring their strong chassis and masking the deficit of their Renault engine.
And Ricciardo started the weekend well with third fastest time in the first session.
Kvyat's performance in the second session was all the more impressive because he suffered engine problems in the first and hardly ran at all.
But the Russian, having a strong first season in the senior Red Bull team after a briefly shaky start, was immediately on the pace in the second session.
Kvyat was third fastest on the harder 'soft' tyres on the first runs, behind Hamilton and Raikkonen, before his fastest time on his qualifying simulation run on the faster super-softs.
Red Bull's performance suggests their hopes of battling with Ferrari for the honour of being next best behind Mercedes could be fulfilled.
Mercedes playing it cool
Mercedes F1 boss Toto Wolff said the team were not happy with their pace on either of the two types of tyre. But it is highly unlikely that they will suddenly have been leapfrogged by two of their rivals, but it was still a surprise not to see a silver car at the front of the field.
Hamilton enters the weekend with a 53-point advantage over Rosberg in the championship, determined not to be distracted and to keep focusing on winning each race.
Rosberg had looked more comfortable in the first session, heading Hamilton by 0.3secs and being consistently faster throughout the session.
But Hamilton turned the tables in the second and was clearly the faster Mercedes driver throughout.
Even on the race runs, Red Bull and Ferrari appeared to have an edge on Mercedes.
But few people in the paddock will expect to see anything else other than Mercedes at the front once they turn up the power of their engines for final practice and qualifying on Saturday.
The team are running a new-spec engine, first introduced at the last race in Italy, and there were reliability concerns with the one in Rosberg's car, to the extent that it had to be removed before qualifying and another new one fitted for this race, his fourth and final one for the year.
McLaren on the up
Like Red Bull, and for similar reasons, McLaren expect Singapore to provide one of their best chances of a strong result.
The Honda engine's inefficiency in terms of hybrid performance left them helpless in the last two races on high-speed tracks in Belgium and Italy.
But the shorter straights of Singapore mean the engine's shortage of electric boost is less of a problem and Alonso, something of a specialist on this track, looked convincing on his way to the eighth fastest time, which was only 0.817secs off the pace.
Team-mate Jenson Button had a less happy time, setting the 14th fastest time 0.929secs behind Alonso.
Nightmare for Manor
It has been a difficult weekend for the back-of-the-grid Manor team.
They drafted in American Alexander Rossi at short notice ahead of the weekend, to replace Spaniard Robert Merhi for five of the remaining seven races this season.
Rossi was doing well, on team-mate Will Stevens's pace, until he crashed at Turn 18 with a few minutes to go in the first session.
The team were unable to get the car repaired for the start of second practice, and their day became even worse when Stevens spun into the barrier at Turn 11 early on.
Rossi's car was repaired in time for him to get out for the last 20 minutes of second practice.