Casey Stoner returned to the front in final MotoGP practice at Laguna Seca, while his title rival Jorge Lorenzo had a massive crash.
World champion Lorenzo's violent high-side came at Turn 5 on his last lap. He landed heavily and was hit by his Yamaha as they slid through the run-off.
After some anxious moments in which Lorenzo lay in the sand trap holding his right leg, the Spaniard managed to stand up and limp away with assistance from medics.
Before Lorenzo's accident, the big news of the session was how close the battle at the front had been, with just 0.049 seconds covering the top three.
Although Honda rider Stoner's 1m21.806s kept him on top for the majority of the morning, there was never much between the championship leader, his team-mate Dani Pedrosa and Lorenzo.
By the halfway point, they were within 0.083s of each other, with the margin then closing to first 0.066s, then 0.049s by the end, with Stoner and Pedrosa 0.017s apart in first and second.
Behind Lorenzo, Marco Simoncelli (Gresini Honda) beat Ben Spies' Yamaha and Andrea Dovizioso's Honda to fourth.
The Ducatis of Nicky Hayden and Valentino Rossi both spent a while in the top six before ending up seventh and eighth. Hayden has returned to the GP11 for today, with Rossi sticking with the 2012-chassis-based GP11.1.
Alvaro Bautista (Suzuki) and Hector Barbera (Aspar Ducati) both had trips through the gravel before taking ninth and 10th.
Other riders to crash were Cardion AB Ducati's Karel Abraham and LCR Honda's Toni Elias. Both were unhurt and able to rejoin - with Elias having to nurse his bike back to the pits for repairs as his spare is being used by guest rider Ben Bostrom this weekend.
Pos Rider Team/Bike Time Gap
1. Casey Stoner Honda 1m21.806s
2. Dani Pedrosa Honda 1m21.823s + 0.017s
3. Jorge Lorenzo Yamaha 1m21.855s + 0.049s
4. Marco Simoncelli Gresini Honda 1m22.222s + 0.416s
5. Ben Spies Yamaha 1m22.325s + 0.519s
6. Andrea Dovizioso Honda 1m22.356s + 0.550s
7. Nicky Hayden Ducati 1m22.432s + 0.626s
8. Valentino Rossi Ducati 1m22.647s + 0.841s
9. Alvaro Bautista Suzuki 1m22.840s + 1.034s
10. Hector Barbera Aspar Ducati 1m22.877s + 1.071s
11. Colin Edwards Tech 3 Yamaha 1m23.062s + 1.256s
12. Randy de Puniet Pramac Ducati 1m23.080s + 1.274s
13. Cal Crutchlow Tech 3 Yamaha 1m23.143s + 1.337s
14. Hiroshi Aoyama Gresini Honda 1m23.513s + 1.707s
15. Karel Abraham Cardion Ducati 1m23.544s + 1.738s
16. Loris Capirossi Pramac Ducati 1m24.038s + 2.232s
17. Toni Elias LCR Honda 1m24.056s + 2.250s
18. Ben Bostrom LCR Honda 1m25.934s + 4.128s