Valentino Rossi grabbed the fastest time in Friday practice at Laguna Seca as the Yamahas usurped Casey Stoner in the closing stages.
Ducati rider Stoner had held the advantage of much of the hour, edging steadily further away from the rest of the pack. But Yamaha duo Rossi and Jorge Lorenzo, who have taken one-two finishes ahead of Stoner in the last two grands prix, crept closer to the Australian's time, and then both jumped ahead, with Lorenzo holding the top spot going into the final runs.
Stoner managed to reclaim second from Rossi but was still 0.063 seconds behind Lorenzo.
Then with his final lap of the day, Rossi became the only man to lap under 1m22s, producing a 1m21.981s to beat Lorenzo by 0.112sec and Stoner by 0.189sec.
Once again this trio had a big margin over their rivals, with fourth placed Dani Pedrosa 0.656s adrift on the best of the works Hondas. He led Toni Elias' factory-specification Gresini bike, and the seconds works Honda of Andrea Dovizioso.
Marco Melandri took an excellent seventh for Hayate Kawasaki, with double Laguna podium finisher Chris Vermeulen recovering from an early error to take eighth on his Suzuki.
Colin Edwards (Tech 3 Yamaha) and Alex de Angelis (Gresini Honda) completed the top ten.
Returning to his home track did little for Nicky Hayden's fortunes. The Ducati rider, twice a winner at Laguna Seca, could only manage 14th, 1.6sec behind teammate Stoner.TIMES:
Pos Rider Bike Time Gap
1. Valentino Rossi Yamaha 1m21.981s
2. Jorge Lorenzo Yamaha 1m22.093s + 0.112s
3. Casey Stoner Ducati 1m22.170s + 0.189s
4. Dani Pedrosa Honda 1m22.637s + 0.656s
5. Toni Elias Gresini Honda 1m22.682s + 0.701s
6. Andrea Dovizioso Honda 1m22.880s + 0.899s
7. Marco Melandri Hayate Kawasaki 1m23.140s + 1.159s
8. Chris Vermeulen Suzuki 1m23.217s + 1.236s
9. Colin Edwards Tech 3 Yamaha 1m23.285s + 1.304s
10. Alex de Angelis Gresini Honda 1m23.406s + 1.425s
11. Randy de Puniet LCR Honda 1m23.439s + 1.458s
12. Loris Capirossi Suzuki 1m23.637s + 1.656s
13. James Toseland Tech 3 Yamaha 1m23.690s + 1.709s
14. Nicky Hayden Ducati 1m23.747s + 1.766s
15. Sete Gibernau Hernando Ducati 1m24.533s + 2.552s
16. Gabor Talmacsi Scot Honda 1m24.926s + 2.945s
17. Niccolo Canepa Pramac Ducati 1m25.511s + 3.530s