Casey Stoner was quickest again in afternoon practice at Catalunya, this time coming out on top during a late rush on a drying track.
The morning rain meant poor track conditions for most of the session, with Honda rider Stoner fastest by two seconds in the wet part of the running - though not everyone was pushing at that stage, with local hero Jorge Lorenzo preferring to not even run until the circuit was ready for slicks with 15 minutes to go.
Suzuki's Alvaro Bautista and Pramac Ducati's Randy de Puniet had brief moments of glory thanks to early changes to slicks, before Stoner thrust his Honda back to the front on dry rubber.
He continually improved his time until reaching a final benchmark of 1m42.940s.
Gresini Honda's Marco Simoncelli was his main rival, and got close to briefly heading Stoner on one run before a mistake in the final part of the lap. He ended up half a second adrift in second.
Andrea Dovizioso completed a one-two-three for the factory-spec Hondas, ahead of the two works Yamahas, with Lorenzo a second clear of team-mate Ben Spies.
Valentino Rossi was top Ducati rider in sixth, followed by Tech 3 Yamaha's Cal Crutchlow.
The latter's team-mate Colin Edwards had the only accident of the session, falling at Turn 5. He had to removed from the scene on a stretcher and was taken to the circuit's medical centre for a shoulder injury to be investigated.
Pos Rider Team/Bike Time Gap 1. Casey Stoner Honda 1m42.940s 2. Marco Simoncelli Gresini Honda 1m43.468s + 0.528s 3. Andrea Dovizioso Honda 1m43.603s + 0.663s 4. Jorge Lorenzo Yamaha 1m43.810s + 0.870s 5. Ben Spies Yamaha 1m44.859s + 1.919s 6. Valentino Rossi Ducati 1m44.944s + 2.004s 7. Cal Crutchlow Tech 3 Yamaha 1m45.136s + 2.196s 8. Hiroshi Aoyama Gresini Honda 1m45.666s + 2.726s 9. Nicky Hayden Ducati 1m45.715s + 2.775s 10. Alvaro Bautista Suzuki 1m45.751s + 2.811s 11. Toni Elias LCR Honda 1m45.760s + 2.820s 12. Randy de Puniet Pramac Ducati 1m46.126s + 3.186s 13. Karel Abraham Cardion Ducati 1m46.280s + 3.340s 14. Loris Capirossi Pramac Ducati 1m46.366s + 3.426s 15. Hector Barbera Aspar Ducati 1m46.501s + 3.561s 16. Colin Edwards Tech 3 Yamaha 1m51.512s + 8.572s