Title favourite Lando Norris was fastest for Formula One champions McLaren after a power cut disrupted the first day of pre-season testing in Bahrain on Wednesday.
The track action was extended by an hour into the evening to compensate after a power cut plunged garages into darkness and brought out red flags.
Sakhir circuit authorities said the outage was caused by an external substation failure.
Ferrari’s Charles Leclerc had been
