Singapore - Ferrari drivers Sebastian Vettel and Kimi Raikkonen set the two fastest times in Saturday's pre-qualifying practice session at the 2015 Singapore GP.
Red Bull drivers Daniil Kvyat and Daniel Ricciardo were third and fourth respectively, extending the pattern of Friday's practice sessions when the Ferraris and Red Bulls both got the better of the previously dominant Mercedes team.
Lewis Hamilton, who has a strong lead in the drivers' championship, was fifth fastest - ahead of his Mercedes team mate Nico Rosberg.
As it happened: 2015 Singapore GP - Third practice
With Ferrari thriving in the hot conditions, and the nimble but power-light Red Bull performing well on the slow street-circuit corners, those teams look capable of ending Mercedes' run of 12 consecutive pole positions this season.
2015 Singapore Grand Prix at Marina Bay Street Circuit:
Third practice
1 Sebastian Vettel (Germany) Ferrari 1min45.682
2 Kimi Raikkonen (Finland) Ferrari 1min46.132
3 Daniil Kvyat (Russia) Red Bull - Renault 1min46.167
4 Daniel Ricciardo (Australia) Red Bull - Renault 1min46.359
5 Lewis Hamilton (Britain) Mercedes 1min46.802
6 Nico Rosberg (Germany) Mercedes 1min47.223
7 Fernando Alonso (Spain) McLaren 1min47.237
8 Carlos Sainz Jr (Spain) Toro Rosso - Renault 1min47.301
9 Max Verstappen (Netherlands) Toro Rosso - Renault 1min47.464
10 Marcus Ericsson (Sweden) Sauber - Ferrari 1min47.568
11 Valtteri Bottas (Finland) Williams-Mercedes 1min47.587
12 Nico Hulkenberg (Germany) Force India - Mercedes 1min47.640
13 Jenson Button (Britain) McLaren 1min47.715
14 Felipe Massa (Brazil) Williams-Mercedes 1min47.733
15 Pastor Maldonado (Venezuela) Lotus - Mercedes 1min47.817
16 Sergio Perez (Mexico) Force India - Mercedes 1min48.002
17 Romain Grosjean (France) Lotus - Mercedes 1min48.116
18 Felipe Nasr (Brazil) Sauber - Ferrari 1min48.932
19 Alexander Rossi (U.S.) Marussia - Ferrari 1min52.588
20 Will Stevens (Britain) Marussia - Ferrari 1min55.293