Nico Rosberg beat Mercedes team-mate Lewis Hamilton to the fastest time in final practice for Formula 1's Malaysian Grand Prix at Sepang.
Last year's title fight runner up Rosberg was quickest after the early runs on the hard-compound Pirelli tyres as Hamilton struggled with the brakes, locking up twice at Turn 9.
And in the final 10 minutes of the session, as drivers bolted on the medium tyres for their qualifying simulation runs, Rosberg improved by seven tenths to clock a 1m39.690s.
Hamilton complained that the "braking is all over the place" when he ran the hard tyres early in the session and when he fitted the mediums, his best time was 0.184s adrift of Rosberg.
The circuit was offering little grip in the 62C degree track temperatures, which combined with high-energy corners and heavy tyre degradation.
That caught a number of drivers out. Sergio Perez and Felipe Nasr were among the drivers to take trips off the road, there were countless severe lock-ups and Roberto Merhi spun at Turn 9 and just managed to keep the Manor out of the gravel.
The Ferraris proved to be Mercedes' closest challengers, with Kimi Raikkonen setting the fastest first sector of all on his way to the third fastest time, 0.555s behind Rosberg, and Sebastian Vettel a few thousandths further back.
Felipe Massa had a couple of off-track excursions early in the session before clocking the fifth fastest time, 0.701s off the pace and a few thousandths quicker than Williams team-mate Valtteri Bottas in sixth.
Red Bull's Daniel Ricciardo was among the first on track, the Australian managing 19 laps in total and ending the one-hour session seventh ahead of the two Toro Rossos of Carlos Sainz and Max Verstappen.
Sauber driver Marcus Ericsson completed the top 10, just edging out the two Lotuses of Romain Grosjean and Pastor Maldonado.
Daniil Kvyat asked for set-up changes on his Red Bull midway through the session after telling the team it had made a "step back". He ended up 13th, ahead of Force India's Nico Hulkenberg.
Fernando Alonso was 2.3s off the pace, finishing in 15th ahead of the second Force India of Sergio Perez, Sauber's Felipe Nasr and McLaren team-mate Jenson Button.
The Manors brought up the rear, with Merhi heading team-mate Will Stevens.
Merhi's time of 1m46.647s was fractions inside 107 per cent - the margin required in Q1 to ensure qualification - which means both Manor drivers have achieved the feat this weekend.
PRACTICE THREE TIMES:
|7||Daniel Ricciardo||Red Bull/Renault||1m40.590s||0.900s||19|
|8||Carlos Sainz Jr.||Toro Rosso/Renault||1m40.601s||0.911s||19|
|9||Max Verstappen||Toro Rosso/Renault||1m40.989s||1.299s||18|
|13||Daniil Kvyat||Red Bull/Renault||1m41.775s||2.085s||14|
|14||Nico Hulkenberg||Force India/Mercedes||1m41.804s||2.114s||15|
|16||Sergio Perez||Force India/Mercedes||1m42.099s||2.409s||14|