Nico Rosberg set the pace once again in the third and final practice session ahead of the Singapore GP, but Red Bull's Max Verstappen was within touching distance as Lewis Hamilton's scrappy weekend continued.
Rosberg clocked a 1:44.352 on the ultrasoft rubber to finish quickest, but Verstappen was only six hundredths adrift with a very impressive lap, and one which suggests Mercedes may have a fight on their hands in qualifying.
Kimi Raikkonen was half a second off Rosberg's benchmark in third, while Daniel Ricciardo could only manage fourth after encountering traffic in the shape of Esteban Ocon through the final sector.
Singapore specialist Sebastian Vettel again struggled with the set-up of his Ferrari and wound up fifth ahead of Force India's Nico Hulkenberg.
After being sidelined for much of FP2 with a hydraulic failure, Lewis Hamilton endured a difficult morning as a pair of lock-ups into Turn 7, the second following a purple Sector 1, denied him a representative lap time.
The championship leader finished the session eighth, sandwiched between the Toro Rossos of Daniil Kvyat and Carlos Sainz.
Valtteri Bottas completed the top ten for Williams, with Sergio Perez 11th and Fernando Alonso 12th in a disappointing session for McLaren, who have thus far failed to deliver on their pre-race potential.
Esteban Gutierrez took 13th, with Felipe Massa 14th, Kevin Magnussen 15th and Jenson Button down in P16.
Sauber languished near the foot of the order once again as Felipe Nasr and Marcus Ericsson wound up 17th and 19th respectively, separated by Romain Grosjean, left to lament his ongoing balance struggles.
Jolyon Palmer was 20th, while Manor pair Pascal Wehrlein, who damaged his rear wing with an early shunt, and Esteban Ocon propped up the order.