Casey Stoner recovered from a crash to grab the fastest time in a fierce battle at the end of Saturday morning MotoGP practice at Indianapolis.
For most of the season the lead had been swapped between Spanish rivals Jorge Lorenzo (Yamaha) and Dani Pedrosa (Honda). But with five minutes to go, they were usurped by Pedrosa's Honda teammate Andrea Dovizioso, who produced a 1m40.432s lap to beat previous pacesetter Lorenzo by 0.2sec.
Stoner had endured a fraught session - first a knee-slider flew off after he clipped a curb early on, then he crashed under braking for Turn 6 and slid deep into the gravel. Once back out on his spare bike, Stoner was on the pace again and closed to within 0.004sec of Dovizioso with his penultimate lap.
Pedrosa then usurped Dovizioso at the front and established a Honda one-two for a few moments before the closely-following Stoner put Ducati on top with a 1m40.331s lap.
Behind the Hondas, Lorenzo found himself fourth, followed by Nicky Hayden on the second works Ducati. Tech 3 Yamaha continued its strong form on its riders' home ground as Ben Spies and Colin Edwards took sixth and eighth, split by Gresini Honda rider Marco Simoncelli.
Valentino Rossi was a low-key ninth though as his tough weekend continued. He crashed his Yamaha near the end of the session, but without causing further damage to his previous injuries.
Pramac Ducati's Aleix Espargaro took the final top 10 spot ahead of Aspar's Hector Barbera, the only other man to fall during the hour.
Pos Rider Team Time Gap
1. Casey Stoner Ducati 1m40.331s
2. Dani Pedrosa Honda 1m40.389s + 0.058s
3. Andrea Dovizioso Honda 1m40.432s + 0.101s
4. Jorge Lorenzo Yamaha 1m40.642s + 0.311s
5. Nicky Hayden Ducati 1m40.878s + 0.547s
6. Ben Spies Tech 3 Yamaha 1m41.061s + 0.730s
7. Marco Simoncelli Gresini Honda 1m41.136s + 0.805s
8. Colin Edwards Tech 3 Yamaha 1m41.192s + 0.861s
9. Valentino Rossi Yamaha 1m41.232s + 0.901s
10. Aleix Espargaro Pramac Ducati 1m41.354s + 1.023s
11. Hector Barbera Aspar Ducati 1m41.390s + 1.059s
12. Alvaro Bautista Suzuki 1m41.715s + 1.384s
13. Marco Melandri Gresini Honda 1m41.783s + 1.452s
14. Randy de Puniet LCR Honda 1m41.876s + 1.545s
15. Mika Kallio Pramac Ducati 1m41.922s + 1.591s
16. Loris Capirossi Suzuki 1m41.975s + 1.644s
17. Hiroshi Aoyama Interwetten Honda 1m42.517s + 2.186s