The first official grand prix track session to be held at Silverstone since 1986 ended with Marc Marquez fastest in 125cc free practice for Sunday's British Grand Prix.
In dry but overcast conditions Marquez - who took his first ever grand prix victory last time out at Mugello - lapped the freshly modified circuit in a best time of 2m 15.835s.
The Red Bull Ajo Derbi rider replaced long-time leader Pol Espargaro at the top of the timesheets with 15 minutes of the hour to go and just held on to the flag by 0.016sec.
An unknown circuit it may have been, but there were few surprises at the front of the field with Espargaro's Tuenti Derbi team-mate Efren Vasquez third and home star Bradley Smith fourth.
Smith's Aspar Aprilia team-mate and title leader Nicolas Terol, who starts round five with a six point lead over Espargaro, claimed fifth place, 0.699sec from the top.
Danny Webb made it two Brits in the top eight, while fastest of the wild-cards was countryman Danny Kent in 24th.
Malaysian rider Zulfahmi Khairuddin christened the circuit with its first official crash by highsiding from his AirAsia backed Aprilia (AirAsia are also sponsoring the race) at turn 13 (the new arrowhead section) in the opening eight minutes. Half an hour later he had another, near identical fall, at the penultimate Luffield turn.
Friday practice - Silverstone:
1. Marquez (Derbi) 2m 15.835s
2. Espargaro (Derbi) +0.016s
3. Vazquez (Derbi) +0.203s
4. Smith (Aprilia) +0.433s
5. Terol (Aprilia) +0.699s
6. Krummenacher (Aprilia) +1.726s
7. Koyama (Aprilia) +2.395s
8. Webb (Aprilia) +2.572s
9. Zarco (Aprilia) +2.586s
10. Cortese (Derbi) +2.778s
24. Kent (Honda) +5.586s
26. Lodge (Honda) +7.127s
27. Mackenzie (Honda) +7.668s
29. Brown (Honda) +8.121s
31. Reid (Honda) +11.975s