MotoGP championship contender Dani Pedrosa set a best time under the official race lap record on his way to the top of Friday's opening practice session for the Malaysian Grand Prix at Sepang.
But the Repsol Honda star was only 0.152s clear of team-mate Casey Stoner, with title leader Jorge Lorenzo 0.313s from the top in third for Yamaha. Pedrosa is 28 points behind Lorenzo with three rounds to go.
World champion Stoner had struggled with his healing ankle on the way to fifth in his MotoGP comeback last Sunday at Motegi - when Pedrosa set a new personal record with his fifth win of the season - but the Australian looked far stronger this morning.
Stoner's best time came on his 14th and final lap.
The track was slippery in FP1, prompting most riders to fit the softer slicks front and rear, and significant time gains can be expected as the weekend goes on - and possibly the first official sub two-minute lap, something Stoner achieved in pre-season testing with the new 1000cc bikes.
Fourth this morning was Andrea Dovizioso (+0.6s), followed by Tech 3 Yamaha team-mate Cal Crutchlow and Lorenzo's Factory Yamaha team-mate Ben Spies (+0.737s).
LCR Honda's Stefan Bradl was seventh and the final rider within one-second of Pedrosa.
Nicky Hayden led the Ducati challenge in eighth place, with Alvaro Bautista (Honda Gresini) and Hector Barbera (Pramac Ducati) completing the top ten.
Valentino Rossi's weekend got off to a disappointing start with eleventh (+1.653s) on the second factory Ducati. The Italian, who ran on at the final turn after missing his braking point, had also struggled during February's final pre-season test at the circuit.
A 1.3s gap separated Rossi from last of the manufacturer riders, Cardion AB Ducati's Karel Abraham, with Randy de Puniet edging out Aspar team-mate Aleix Espargaro by a few hundredths to be the top CRT rider.
The CRTs are likely to suffer more than usual this weekend, due to the two long straights.
A plaque in memory of Marco Simoncelli, who lost his life in last year's race, was unveiled at Turn 11 on Thursday.
Second practice takes place this afternoon.
Friday practice (1):
1. Dani Pedrosa
2. Casey Stoner
3. Jorge Lorenzo
4. Andrea Dovizioso
5. Cal Crutchlow
6. Ben Spies
7. Stefan Bradl
8. Nicky Hayden
9. Alvaro Bautista
10. Hector Barbera
11. Valentino Rossi
12. Karel Abraham
13. Randy De Puniet
14. Aleix Espargaro
15. Colin Edwards
16. Michele Pirro
17. James Ellison
18. Roberto Rolfo
19. Yonny Hernandez
20. Ivan Silva
21. Danilo Petrucci