Dani Pedrosa edged Honda works team-mate Casey Stoner by just 12 hundredths of a second in the final MotoGP practice session at Estoril.
The fight for top spot came down to the two Honda riders, with the lead changing hands several times over the session before Pedrosa eventually sealed the issue with a 1m37.325s.
For a long while no-one else was able to join Honda in dipping under the 1m38s mark, but with 12 minutes to run Jorge Lorenzo got in on the act to go third fastest, just over three tenths down on Pedrosa.
Tech 3 Yamaha duo Cal Crutchlow and Andrea Dovizioso were next up in fourth and fifth. Dovizioso had led the inter-team battle in the early stages, but was demoted to fifth by Crutchlow with 18 minutes to run.
Late improvements sent Ducati's Valentino Rossi and then Gresini Honda's Alvaro Bautista into sixth.
Rossi had elected to run the harder compound tyre for much of the session - in contrast to the majority of the field - and ran around 10th as a consequence.
He jumped up to sixth in the final minute however, although Bautista, who was still on circuit, managed to then push the Italian down to seventh.
The second works Yamahas and Ducatis of Ben Spies and Nicky Hayden beat LCR Honda's Stefan Bradl to eighth and ninth.
Randy de Puniet once again finished top of the CRT pile. For a long time he was faster than the satellite bikes of Hector Barbera and Karel Abraham, although Barbera was able to find late improvements to move ahead of the Frenchman and into 11th.
Pos Rider Team/Bike Time Gap 1. Dani Pedrosa Honda 1m37.326s 2. Casey Stoner Honda 1m37.338s + 0.012s 3. Jorge Lorenzo Yamaha 1m37.680s + 0.354s 4. Cal Crutchlow Tech 3 Yamaha 1m38.086s + 0.760s 5. Andrea Dovizioso Tech 3 Yamaha 1m38.273s + 0.947s 6. Alvaro Bautista Gresini Honda 1m38.332s + 1.006s 7. Valentino Rossi Ducati 1m38.443s + 1.117s 8. Ben Spies Yamaha 1m38.558s + 1.232s 9. Nicky Hayden Ducati 1m38.602s + 1.276s 10. Stefan Bradl LCR Honda 1m38.714s + 1.388s 11. Hector Barbera Pramac Ducati 1m38.856s + 1.530s 12. Randy de Puniet Aspar Aprilia 1m39.361s + 2.035s 13. Aleix Espargaro Aspar Aprilia 1m40.225s + 2.899s 14. Karel Abraham Cardion Ducati 1m40.374s + 3.048s 15. Yonny Hernandez Avintia FTR-Kawasaki 1m40.561s + 3.235s 16. Mattia Pasini Speed Master Aprilia 1m40.875s + 3.549s 17. Michele Pirro Gresini FTR-Honda 1m41.379s + 4.053s 18. Ivan Silva Avintia Inmotec-Kawasaki 1m41.772s + 4.446s 19. Danilo Petrucci Ioda-Aprilia 1m42.002s + 4.676s 20. James Ellison Paul Bird Aprilia 1m42.103s + 4.777s 21. Colin Edwards Forward Suter-BMW 1m42.145s + 4.819s