Ferrari dominated Friday morning's opening free practice for this weekend's Bahrain Grand Prix, with Brazilian Felipe Massa topping the times ahead of team-mate Fernando Alonso of Spain.
In typically hot conditions, with a track temperature of 41 degrees Celsius (105.8 degrees Fahrenheit) and an air temperature of 34C at the Sakhir circuit, the Ferrari duo took command in the final half hour of the 90-minute session.
Less than a week after Alonso's commanding triumph in last Sunday's Chinese Grand Prix, it was a clear demonstration of the Ferrari outfit's speed and strength as they seek to end Red Bull's run of world championship successes.
The main title contender teams delayed their entry into the fray at the dusty, sand-swept circuit 25km (15.5 miles) outside Manama until well into the session and Ferrari were the last team out to show their speed with an hour gone -- but they immediately rose to the top.
After Alonso had initially set the pace, Massa took over and clocked the fastest lap in 1min 34.487secs, his time beating Alonso by 0.077secs at the end of a session mostly devoted to testing tyres with high fuel loads.
German Nico Rosberg was third for Mercedes ahead of compatriot and defending triple world champion Sebastian Vettel of Red Bull, Briton Paul di Resta of Force India and Briton Jenson Button in the improving McLaren.
Australian Mark Webber was seventh for Red Bull ahead of German Adrian Sutil in the second Force India, Finn Kimi Raikkonen and his Lotus team-mate Frenchman Romain Grosjean.
Briton Lewis Hamilton, who took pole position last weekend in Shanghai, was down in 13th place in the second Mercedes, an unexpected spot but presumed to be due to his running a different programme in the session to his team-mate Rosberg.