Valentino Rossi set the quickest time in the opening practice session for this weekend's MotoGP round at Motegi, knocking Casey Stoner off the top spot with his last lap of the session.
It is the first time this season that a session has not been topped by Stoner's Ducati, although the Australian was fastest for the majority of the 45-minute practice.
Stoner had two excursions off track during the session, one at Turn 1 and one at the hairpin, but he escaped unscathed on both occasions and was the first rider to break into the 1m48s in the last quarter of an hour.
He returned to the pits with the best lap at the end of his final run, but reigning world champion Rossi found a chunk of time in the last sector of his last lap and posted a time half a tenth faster.
Jorge Lorenzo's factory Yamaha had a spell at the head of the timesheet, but was shuffled down to third as Rossi and Stoner trimmed their times at the end.
The works Suzukis ran well throughout the session, with Chris Vermeulen ending up fourth and Loris Capirossi sixth. They were separated by Colin Edwards' Tech 3 Yamaha in fifth.
Honda had a dismal session and rookie Japanese rider Yuki Takahasi spent most of it as the manufacturer's quickest representative on the fringes of the top 10, despite a trek through the gravel mid-way through.
The factory Hondas of Andrea Dovizioso and Dani Pedrosa were well off the leaders' pace, although Dovizioso at least managed to salvage seventh place with his last lap of the session.
Marco Melandri was eighth quickest on the sole Kawasaki, ahead of Toni Elias's Gresini Honda and James Toseland's Tech 3 Yamaha.
The only faller was Mika Kallio, who had his first accident in MotoGP's top class when he was thrown from his Pramac Ducati in a high-side crash at Turn 3. The Finn landed awkwardly on top of his bike, but was uninjured and returned to the track later in the session.
Pos Rider Team Time Gap
1. Valentino Rossi Yamaha 1m48.545s
2. Casey Stoner Ducati 1m48.601s +0.056
3. Jorge Lorenzo Yamaha 1m48.965s +0.420
4. Chris Vermeulen Suzuki 1m49.382s +0.837
5. Colin Edwards Tech 3 Yamaha 1m49.697s +1.152
6. Loris Capirossi Suzuki 1m49.980s +1.435
7. Andrea Dovizioso Honda 1m50.030s +1.485
8. Marco Melandri Hayate Kawasaki 1m50.123s +1.578
9. Toni Elias Gresini Honda 1m50.209s +1.664
10. James Toseland Tech 3 Yamaha 1m50.342s +1.797
11. Dani Pedrosa Honda 1m50.391s +1.846
12. Nicky Hayden Ducati 1m50.393s +1.848
13. Yuki Takahashi Scot Honda 1m50.404s +1.859
14. Sete Gibernau Hernando Ducati 1m50.538s +1.993
15. Alex de Angelis Gresini Honda 1m50.601s +2.056
16. Randy de Puniet LCR Honda 1m50.669s +2.124
17. Mika Kallio Pramac Ducati 1m51.643s +3.098
18. Niccolo Canepa Pramac Ducati 1m51.929s +3.384