2008 Indianapolis Grand Prix winner and victor last time out at Brno, Nicolas Terol, was back on top of the 125cc timesheets during Friday free practice for the 2009 Indy event.
The one-hour session took place in overcast conditions, with light rain falling in the final six minutes and effectively bringing the session to an early end, leaving Terol 0.111sec clear of nearest rival Simone Corsi.
Bradley Smith was third fastest with Simone Cortese the leading non-Aprilia rider in a close fourth for the Ajo Derbi squad.
World championship leader Julian Simon, who starts round eleven 54.5 points ahead of Terol, was ninth fastest - but only 0.6sec from the top.
Friday practice - Indianapolis:
1. Terol (Aprilia) 1min 50.603sec
2. Corsi (Aprilia) +0.111sec
3. Smith (Aprilia) +0.275sec
4. Cortese (Derbi) +0.293sec
5. Marquez (KTM) +0.360sec
6. Vazquez (Derbi) +0.503sec
7. Bradl (Aprilia) +0.553sec
8. Gadea (Aprilia) +0.607sec
9. Simon (Aprilia) +0.616sec
10. Olive (Derbi) +0.768sec
12. Redding (Aprilia) +1.185sec
18. Webb (Aprilia) +1.888sec