Nico Rosberg put a crash in the first practice session behind him to set the pace in FP2 and team-mate Lewis Hamilton was left frustrated by issues with his Mercedes at the Singapore Grand Prix on Friday.
Rosberg, racing in his 200th Grand Prix, has won both races since the mid-season break to reduce championship leader Hamilton's advantage to just two points and laid down a marker by clocking the fastest lap under the lights at Marina Bay.
The German lost his wing in a smash after smashing into the barriers at Turn 18 late in the opening practice session and was only fifth-quickest, with Hamilton fourth as Red Bull duo Max Verstappen and Daniel Ricciardo made an early statement by finishing FP1 first and second respectively.
Normal service was resumed for Rosberg later in the day, with a circuit of one minute and 44.152 seconds putting him on top of the timesheets.
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Hamilton was seventh as he struggled with ultrasoft tyres and could only manage 10 laps in FP2 before a hydraulic issue left him kicking his heels in the garage at a venue where he retired last year and can ill afford a repeat on Sunday.
Ferrari's Kimi Raikkonen was second-quickest, 0.275secs slower than Rosberg, with Verstappen following up his impressive start by sitting third ahead of team-mate Ricciardo.
Sebastian Vettel, winner in Singapore last year, was fifth and Nico Hulkenberg for Force India.
Red Bull have been tipped to pose more of a challenge to Mercedes this weekend and they showed why in FP1, with Verstappen leading the way just 0.049secs faster than Ricciardo courtesy of a lap of 1:45.823.