Red Bull driver Sebastian Vettel set the fastest time in Friday's practice for the Singapore Grand Prix.
Vettel finished in 1 minute, 44.249 seconds on the Marina Bay circuit; six-tenths of a second ahead of teammate Mark Webber.
He's chasing his third straight win in Formula One's annual night race. He's also aiming for a fourth consecutive drivers' championship.
Mercedes drivers Nico Rosberg and Lewis Hamilton were the next nearest rivals, but third-placed Rosberg was more than a second slower than Vettel. Lotus driver Sebastian Grosjean was fifth, outperforming teammate Kimi Raikkonen in eighth.
Ferrari's Fernando Alonso was sixth, ahead of McLaren's Jenson Button. Force India's Adrian Sutil and McLaren's Sergio Perez were ninth and 10th.