Jorge Lorenzo edged Marc Marquez as the 2013 MotoGP title contenders set a blazing pace in first practice at Phillip Island.
Just 0.088 seconds separated the pair at the chequered flag, with Lorenzo eventually prevailing when he dipped down to a 1m29.167s. They had taken turns at the top before the Yamaha rider's late effort.
Honda man Marquez can mathematically wrap up a rookie championship this weekend in Australia, although he needs to outscore Lorenzo by at least eight points.
The two championship rivals were in a class of their own throughout, and were set to finish nearly one second clear of the entire field until several riders improved in the final minutes.
Chief among them was Gresini Honda rider Alvaro Bautista, who produced a 1m29.831s - still some six tenths down on Lorenzo - to steal into third ahead of works counterpart and Sepang winner Dani Pedrosa.
Valentino Rossi meanwhile edged Tech 3 Yamaha's Cal Crutchlow in the fight for fifth, with the Briton in turn less than a quarter of a second clear of team-mate Bradley Smith.
Nicky Hayden, who will join the Aspar squad and ride Honda's production racer next season, was eighth fastest.
Randy de Puniet claimed top CRT honours in ninth, finishing fractions ahead of Ducati's Andrea Dovizioso and Pramac's Andrea Iannone.
Stefan Bradl, riding less than a week after fracturing and then having surgery on his right ankle, managed 11 laps and wound up 20th overall.
He was passed fit to start first practice at Phillip Island, but will need to undergo further medical checks in order to continue competing.
Pos Rider Team/Bike Time Gap Laps 1. Jorge Lorenzo Yamaha 1m29.167s 20 2. Marc Marquez Honda 1m29.255s +0.088s 20 3. Alvaro Bautista Gresini Honda 1m29.831s +0.664s 21 4. Dani Pedrosa Honda 1m30.008s +0.841s 19 5. Valentino Rossi Yamaha 1m30.053s +0.886s 22 6. Cal Crutchlow Tech 3 Yamaha 1m30.130s +0.963s 22 7. Bradley Smith Tech 3 Yamaha 1m30.361s +1.194s 22 8. Nicky Hayden Ducati 1m30.666s +1.499s 20 9. Randy de Puniet Aspar Aprilia 1m31.280s +2.113s 22 10. Andrea Dovizioso Ducati 1m31.295s +2.128s 17 11. Andrea Iannone Pramac Ducati 1m31.295s +2.128s 20 12. Alex Espargaro Aspar Aprilia 1m31.458s +2.291s 18 13. Colin Edwards Forward FTR-Kawasaki 1m31.557s +2.390s 18 14. Hiroshi Aoyama Avintia FTR-Kawasaki 1m31.637s +2.470s 19 15. Hector Barbera Avintia FTR-Kawasaki 1m31.766s +2.599s 18 16. Danilo Petrucci Ioda-Suter-BMW 1m31.803s +2.636s 24 17. Claudio Corti Forward FTR-Kawasaki 1m32.300s +3.133s 17 18. Yonny Hernandez Pramac Ducati 1m32.341s +3.174s 18 19. Bryan Staring Gresini FTR-Honda 1m32.741s +3.574s 20 20. Stefan Bradl LCR Honda 1m33.165s +3.998s 11 21. Luca Scassa Cardion Aprilia 1m33.234s +4.067s 18 22. Lucas Pesek Ioda-Suter-BMW 1m33.797s +4.630s 16 23. Michael Laverty PBM-Aprilia 1m33.875s +4.708s 23 24. Damian Cudlin PBM Aprilia 1m35.906s +6.739s 20