Marco Simoncelli emphasised his status as one of MotoGP's coming men by setting the fastest time in the opening free practice session for the Portuguese MotoGP.
The Italian Gresini rider, who has access to a factory Honda, set his 1m38.032s lap on his last attempt of the session, bumping factory ace Casey Stoner down to second in the process.
Simoncelli's pace will have boosted him and the team, with the 24-year-old keen to bounce back from crashing out of the lead in the Spanish Grand Prix last time out.
Dani Pedrosa made it three Hondas out of three at the top of the order.
World champion and 2011 MotoGP points leader Jorge Lorenzo was fourth fastest.
The Yamaha rider, who has won every MotoGP race he's started at Estoril, set a time of 1m38.413s about halfway through the 45-minute session and stayed there until that late flurry of activity from the Honda men.
In the end, Lorenzo's time was 0.381s off Simoncelli's ultimate mark, but his pace was consistent and the Spaniard also completed more laps than any other rider.
Valentino Rossi was an encouraging fifth fastest for Ducati, though he was more than half a second away from the pace.
Andrea Dovizioso was a distant sixth on the last of the factory Hondas, ahead of Tech 3's Colin Edwards and works Yamaha rider Ben Spies - the second of the two Texans having a spell in the deep gravel at the Parabolica.
Hector Barbera (Aspar Ducati) and Randy de Puniet (Pramac Ducati) completed the top 10.
Ducati's Nicky Hayden ended the session 14th after suffering a technical problem with his race bike out at Turn 6, before returning to the pits to jump on the spare.
Alvaro Bautista was 17th and last on his return from a badly broken leg on the Suzuki, some three seconds slower than Simoncelli's time.
Pos Rider Team/Bike Time Gap 1. Marco Simoncelli Gresini Honda 1m38.032s 2. Casey Stoner Honda 1m38.241s + 0.209s 3. Dani Pedrosa Honda 1m38.259s + 0.227s 4. Jorge Lorenzo Yamaha 1m38.413s + 0.381s 5. Valentino Rossi Ducati 1m38.569s + 0.537s 6. Andrea Dovizioso Honda 1m38.781s + 0.749s 7. Colin Edwards Tech 3 Yamaha 1m38.862s + 0.830s 8. Ben Spies Yamaha 1m38.895s + 0.863s 9. Hector Barbera Aspar Ducati 1m39.042s + 1.010s 10. Randy de Puniet Pramac Ducati 1m39.779s + 1.747s 11. Loris Capirossi Pramac Ducati 1m39.848s + 1.816s 12. Hiroshi Aoyama Gresini Honda 1m39.856s + 1.824s 13. Cal Crutchlow Tech 3 Yamaha 1m40.129s + 2.097s 14. Nicky Hayden Ducati 1m40.199s + 2.167s 15. Toni Elias LCR Honda 1m40.407s + 2.375s 16. Karel Abraham Cardion Ducati 1m40.469s + 2.437s 17. Alvaro Bautista Suzuki 1m41.034s + 3.002s