Bradley Smith finished on top of the timesheets by 0.2sec during Friday practice for the 125cc Malaysian Grand Prix at Sepang.
The Englishman, who lost the race and world championship to team-mate Julian Simon on the final lap of last Sunday's Australian Grand Prix, knocked the new world champion from the top on his 20th and final lap of the session - with KTM's Marc Marquez then squeezing between the Aspar riders.
Smith starts the penultimate round 21 points clear of Nicolas Terol for second in the championship. Terol was fourth fastest on Friday for Jack & Jones Aprilia, 0.625sec from the top.
Friday practice - Sepang:
1. Smith (Aprilia) 2min 14.895sec
2. Marquez (KTM) +0.200sec
3. Simon (Aprilia) +0.306sec
4. Terol (Aprilia) +0.625sec
5. Folger (Aprilia) +0.851sec
6. Cortese (Derbi) +0.858sec
7. Olive (Derbi) +0.946sec
8. Corsi (Aprilia) +1.231sec
9. Rabat (Aprilia) +1.291sec
10. Espargaro (Derbi) +1.411sec
12. Redding (Aprilia) +1.561sec
22. Webb (Aprilia) +2.920sec