Friday's second practice session for the Aragon MotoGP was cancelled after a power cut in Spain.
Electricity problems at the circuit meant that 125cc afternoon practice was delayed, but did take place before further power cuts cancelled the planned MotoGP and Moto2 sessions.
Saturday's morning sessions will be longer to help teams get ready for Sunday's race.
Spanish rider Dani Pedrosa was quickest in Friday's morning session.
Title rivals Jorge Lorenzo and Casey Stoner were second and third, with Marco Simoncelli fourth on his Gresini Honda.
British rider Cal Crutchlow said: "It is obviously disappointing not to have the second session because it hurts me more than the other guys.
"I need to be out there learning the track and you lose the momentum gained. I felt really confident at the end of this morning and was looking forward to this afternoon, but now I've got to build up my pace all over again.
"There's nothing I can do about what happened and I'm confident with more time on track I can climb further up the timesheets."
Simoncelli added: "The cancellation of a practice session due to a power shortage certainly doesn't look good for a World Championship.
"They clearly need to look into it and make sure that things are repaired and that it doesn't happen again."
Aragon practice times:
1. Dani Pedrosa (Spn) Repsol Honda 1'50.281
2. Jorge Lorenzo (Spn) Yamaha 1'50.730
3. Casey Stoner (Aus) Repsol Honda 1'50.806
4. Marco Simoncelli (Ita) Gresini Honda 1'50.893
5. Andrea Dovizioso (Ita) Repsol Honda 1'51.091
6. Randy De Puniet (Fra) Pramac Ducati 1'51.376
7. Nicky Hayden (USA) Ducati 1'51.418
8. Valentino Rossi (Ita) Ducati 1'51.676
9. Colin Edwards (USA) Tech 3 Yamaha 1'51.826
10. Hiroshi Aoyama (Jpn) Gresini Honda 1'51.859
14. Cal Crutchlow (GB) Tech 3 Yamaha 1'52.580