Dani Pedrosa led a works Honda 1-2-3 in second practice at Motegi, as the Japanese marque boosted its hopes of a first home MotoGP win since Makoto Tamada triumphed in 2004.
The Spaniard seized the initiative with 20 minutes to go, becoming the first rider to break the 1m47s barrier before immediately bettering his own mark to set a 1m46.790s, which stood for the remainder of the session.
For a time that put Pedrosa well clear of the field and indeed the previous lap record, a 1m47.091s set by Casey Stoner in 2008.
It was Stoner who came closest to deposing Pedrosa, moving to within 0.054s of his team-mate with four minutes to go.
That late improvement knocked last year's polesitter Andrea Dovizioso into third, with the Italian also under lap record pace.
Gresini Honda's Marco Simoncelli ended the session in fourth, his best effort coming in the very early stages of the session.
Jorge Lorenzo was the top Yamaha rider in fifth, the reigning champion finishing 0.520s down.
Lorenzo's team-mate Ben Spies struggled with illness, leaving his bike to visit the medical centre with 15 minutes to go and finishing down in 14th.
Sixth was claimed by Nicky Hayden, who was again the top Ducati, more than half a second clear of Valentino Rossi in eighth.
The pair were split by the second Gresini Honda of Hiroshi Aoyama, who was the last rider to finish within 1s of Pedrosa.
Hector Barbera (Aspar Ducati) and Colin Edwards (Tech 3 Yamaha) rounded out the top 10 ahead of Alvaro Bautista on the lone Suzuki.
Pos Rider Team/Bike Time Gap 1. Dani Pedrosa Honda 1m46.790s 2. Casey Stoner Honda 1m46.844s + 0.054s 3. Andrea Dovizioso Honda 1m46.952s + 0.162s 4. Marco Simoncelli Gresini Honda 1m47.188s + 0.398s 5. Jorge Lorenzo Yamaha 1m47.310s + 0.520s 6. Nicky Hayden Ducati 1m47.381s + 0.591s 7. Hiroshi Aoyama Gresini Honda 1m47.765s + 0.995s 8. Valentino Rossi Ducati 1m47.975s + 1.185s 9. Hector Barbera Aspar Ducati 1m48.055s + 1.265s 10. Colin Edwards Tech 3 Yamaha 1m48.076s + 1.286s 11. Alvaro Bautista Suzuki 1m48.097s + 1.307s 12. Randy de Puniet Pramac Ducati 1m48.374s + 1.584s 13. Cal Crutchlow Tech 3 Yamaha 1m48.379s + 1.589s 14. Ben Spies Yamaha 1m48.567s + 1.777s 15. Toni Elias LCR Honda 1m48.743s + 1.953s 16. Karel Abraham Cardion Ducati 1m49.305s + 2.515s 17. Kousuke Akiyoshi LCR Honda 1m49.464s + 2.674s 18. Shinichi Itoh Honda 1m49.673s + 2.883s 19. Damian Cudlin Pramac Ducati 1m51.349s + 4.559s