Nico Rosberg dominated the opening practice session for the Bahrain Grand Prix as he led team-mate Lewis Hamilton by half a second, whilst third-placed Kimi Raikkonen lagged 1.8 seconds behind the German.
Ferrari completed much of its running on the medium tyre, whereas Rosberg and Hamilton set their quickest times on the softer compound, which goes someway to explainining the gap between Mercedes and Ferrari.
However it's clear the Anglo-German outfit has the upperhand. Rosberg's best lap was more than two-tenths quicker than Hamilton's 2015 pole lap at the same circuit.
With Raikkonen third, Red Bull's Daniel Ricciardo and Daniil Kvyat completed the top five.
Force India's Nico Hulkenberg was sixth, more than two seconds adrift, whilst the second Force India driven by Alfonso Celis was a further 2.5 seconds back in 21st – just half a second separating him and last-placed Rio Hartyanto.
Carlos Sainz led Max Verstappen in seventh and eighth, with Romain Grosjean and Felipe Massa completing the top ten.
Stoffel Vandoorne made his McLaren debut as he stands in for the recovering Fernando Alonso. The Belgian finished 18th quickest, almost a second down on team-mate Jenson Button, P14.
