Mercedes drivers set the two fastest times in the pre-qualifying practice sessions at the Formula One Malaysian Grand Prix, showing they are the team to beat again for pole position and in Sunday's race.
Nico Rosberg, who won the season-opener in Australia, led the way with a time of 1 minute, 39 seconds at the Sepang International Circuit, a quarter of a second ahead of teammate Lewis Hamilton.
Ferrari's Kimi Raikkonen was third fastest, but more than a second behind Rosberg's time, indicating the silver cars remain in a class of their own in the early stages of the season as all the teams adapt to the new V6 turbo hybrid engines.
Four-time defending world champion Sebastian Vettel, using a new front wing, was fourth fastest, and his Red Bull teammate, Daniel Ricciardo was sixth, separated by Force India's Nico Hulkenberg.
McLaren's engine problems
McLaren suffered engine problems, with their two drivers setting only one timed lap between them.
The early leader in the constructors' championship had major work to do to rectify the problem in the two-hour gap before qualifying.
Ferrari's Fernando Alonso was seventh on the timesheets, ahead of Williams drivers Felipe Massa and Valtteri Bottas.
Lotus drivers Romain Grosjean and Pastor Maldonado, who had almost no running on Friday, did at least manage to complete a full programme of laps, but struggled down in 16th and 17th places nearly three seconds off the pace.
The practice session took place in dry conditions, though rain was forecast for later in the day, which may affect qualifying.