Lewis Hamilton bounced back from an engine issue in the morning to top second practice for the Malaysian Grand Prix.
Hamilton completed just four laps of the Sepang circuit during the opening practice session after a Mercedes power unit problem.
The reigning champion was forced to sit out the opening 30 minutes of running in the afternoon, and had to return to the pits after his opening run after losing all car telemetry.
However, he rallied to post a time of 1:39.790 on the medium Pirelli tyres to top the timesheets, three tenths clear of Ferrari’s Kimi Raikkonen.
The Finn, who briefly topped the session before Hamilton took to the track, ended the day second with a 1:40.160 set on a medium tyres.
Nico Rosberg struggled to set a clean quick lap on the faster medium compound Pirellis and was forced to settle for third in the second Mercedes.
Daniil Kvyat was fourth fastest for Red Bull, but the Russian was forced to pit late in the session due to a technical problem.
Valtteri Bottas and Felipe Massa were fifth and sixth respectively for Williams, ahead of Sebastian Vettel in the Ferrari.
The German had his best lap ruined after Roberto Merhi spun off at Turn 11, prompting a brief red flag, and then went off at the exact same corner on his next flier once the session was restarted.
Max Verstappen was eighth for Toro Rosso, while Marcus Ericsson and Daniel Ricciardo rounded out the top ten.
Pastor Maldonado ended the afternoon 11th for Lotus, ahead of Sauber’s Felipe Nasr, who sat out the opening practice session for Raffaele Marciello.
Carlos Sainz Jr. spilt the two Force Indias of Sergio Perez and Nico Hulkenberg, while Fernando Alonso beat his McLaren team-mate Jenson Button to 16th.
Romain Grosjean was just 17th for Lotus after he suffered a power problem.
Will Stevens was the quickest of the two Manor cars for a second session, as the pair propped up the leaderboard.
Image courtesy of Mercedes AMG PETRONAS