Nico Rosberg, the German-born son of orginal 'flying Finn' and former world champion Keke Rosberg, topped the times again for Williams in the second free practice ahead of Sunday's Bahrain Grand Prix.
The 23-year-old German clocked a best lap of one minute and 33.339 seconds to wind up just one-tenth of a second ahead of nearest rival, two-times drivers' champion Fernando Alonso of Spain in a Renault.
Alonso, who was on the front row of the starting grid in China last weekend, again promised much on Friday as Renault maintained their improvement.
Italian Jarno Trulli was third fastest ahead of German Sebastian Vettel, last Sunday's winner for Red Bull in Shanghai, his Red Bull team-mate Mark Webber and Briton Jenson Button, the world championship leader in a Brawn GP car.
German Adrian Sutil was seventh for Force India ahead of German Timo Glock in the second Toyota and Brazilian Rubens Barrichello in the second Brawn as most of the teams used the session for data-gathering rather than outright performance.