Lewis Hamilton recovered from a disastrous morning to top the first day of practice for the Formula 1 season-opening Australian Grand Prix in his Mercedes.
The 2008 world champion stopped on only his second lap of the first session thanks to a sensor calibration problem, meaning he had not completed a flying lap heading into the afternoon.
Hamilton was one of the last of the frontrunners to set a time on fresh Pirelli soft tyres in practice two, waiting until the second half of the session before setting his time.
A stunning final sector allowed him to depose Mercedes team-mate Nico Rosberg at the top of the timesheets by 0.157 seconds.
Nobody else was able to get close to Rosberg, who had underlined the strength of Mercedes by setting the fastest time achieved on medium-compound Pirellis earlier in the afternoon.
Rosberg looked set to retain his position on the faster rubber after knocking Red Bull driver Daniel Ricciardo, who was among the earliest drivers to bolt on the softs and briefly went fastest, off top spot at around the halfway mark of the 90-minute session, only for Hamilton to show his pace.
Ferrari's Fernando Alonso, who was Rosberg's closest rival on the medium rubber, ended up third fastest, half-a-second off Hamilton.
While the Spaniard was unable to match the Mercedes over the full lap, he was the quickest of all in the first sector at Albert Park.
Sebastian Vettel rounded out an encouraging first day of the season for Red Bull in fourth overall despite an off-track moment at Turn 1 early in the session having dropped a wheel onto the grass at corner entry.
He ended up three-quarters of a second down in fourth place, with team-mate Ricciardo sixth fastest, 0.157s slower than Vettel.
Splitting the Red Bulls was three times Australian GP winner Jenson Button, who was fastest in sector two but struggled with understeer.
Kimi Raikkonen was seventh fastest, although his session was interrupted by what is believed to have been a gearbox glitch when he was preparing for a practice start.
The lead Williams of Valtteri Bottas was eighth overall, 1.3s down, although on medium rubber the deficit to the Mercedes had been around half that.
Several drivers had off-track moments during the session, with Kevin Magnussen enduring a bumpy ride after running wide exiting Turn 12 early on and Toro Rosso's Jean-Eric Vergne going straight on at Turn 3 and through the gravel trap.
Sauber's Esteban Gutierrez also had a grassy moment exiting Turn 2 while scrapping for territory with Vettel.
Late in the session, Nico Hulkenberg locked the rears under braking for Turn 9 and spun into the gravel.
Almost simultaneously, Romain Grosjean buried his Lotus in the gravel at Turn 6 after losing the rear under braking and slapping the wall with the left-rear corner.
Only 19 drivers were able to set a time, with Kamui Kobayashi's Caterham unable to run thanks to a "power unit-related fuel system issue" that struck in morning practice.
Team-mate Marcus Ericsson was at least able to get onto the circuit, but a hydraulics problem on his installation lap forced him to return to the pits and the team was unable to get him back out again.
Lotus driver Pastor Maldonado did leave the garage, but was unable to make it out of the pitlane after stopping with a suspected ERS problem that the team did not have time to resolve.
This rounded off a dismal day for Lotus, with Grosjean the second slowest of the drivers who did set a time before his late off.
Pos Driver Team/Car Time Gap Laps 1. Lewis Hamilton Mercedes 1m29.625s 37 2. Nico Rosberg Mercedes 1m29.782s +0.157s 31 3. Fernando Alonso Ferrari 1m30.132s +0.507s 28 4. Sebastian Vettel Red Bull-Renault 1m30.381s +0.756s 41 5. Jenson Button McLaren-Mercedes 1m30.510s +0.885s 33 6. Daniel Ricciardo Red Bull-Renault 1m30.538s +0.913s 38 7. Kimi Raikkonen Ferrari 1m30.898s +1.273s 32 8. Valtteri Bottas Williams-Mercedes 1m30.920s +1.295s 38 9. Kevin Magnussen McLaren-Mercedes 1m31.031s +1.406s 34 10. Nico Hulkenberg Force India-Mercedes 1m31.054s +1.429s 33 11. Jean-Eric Vergne Toro Rosso-Renault 1m31.060s +1.435s 35 12. Felipe Massa Williams-Mercedes 1m31.119s +1.494s 31 13. Sergio Perez Force India-Mercedes 1m31.283s +1.658s 36 14. Adrian Sutil Sauber-Ferrari 1m32.355s +2.730s 36 15. Esteban Gutierrez Sauber-Ferrari 1m32.468s +2.843s 26 16. Daniil Kvyat Toro Rosso-Renault 1m32.495s +2.870s 36 17. Jules Bianchi Marussia-Ferrari 1m33.486s +3.861s 29 18. Romain Grosjean Lotus-Renault 1m33.646s +4.021s 12 19. Max Chilton Marussia-Ferrari 1m34.757s +5.132s 29 20. Marcus Ericsson Caterham-Renault 1 21. Pastor Maldonado Lotus-Renault 22. Kamui Kobayashi Caterham-Renault