Ferrari's Sebastian Vettel was fastest in the first day of practice at the Bahrain Grand Prix with the joint Formula One championship leader comfortably quicker than his Mercedes rival Lewis Hamilton.
The German, a four times world champion with Red Bull, lapped 0.400 faster than Red Bull's Australian Daniel Ricciardo in the opening afternoon session and then pipped Mercedes' Valtteri Bottas by 0.041 under the evening floodlights.
Triple world champion Hamilton, who won the previous race in China after Vettel's success in the Australian opener and shares the overall lead with 43 points, was 10th and fifth respectively.
Ricciardo was third in the evening with Ferrari's Kimi Raikkonen fourth after his afternoon session went up in smoke, with the Finn abandoning his smoking car and trudging off in the desert heat.
The solitary walk through the arid landscape in overalls and helmet, before being collected by a scooter, was an arresting sight -- and also typical of a driver with 'Iceman' tattooed on his left arm.
"Walking through the desert in 37C heat. In full race suit. Helmet on. Only the Iceman is cool enough to do it," the official formula1.com website observed on its Twitter feed.
While Raikkonen built up a sweat, Vettel settled in at the top of the timesheets with a best lap of one minute 32.697 seconds. He did 1:31.310 in the cooler evening conditions.
Champions Mercedes had been more focused on longer runs with heavier fuel loads in the searing afternoon heat, with Bottas only 14th, but speeded up in more representative race conditions.
The Mercedes pair did more laps than anyone, however, with Hamilton completing 28 and Bottas 27 in the afternoon compared to Vettel's total of 21 and then 35 each in the later session.
Mercedes non-executive chairman Niki Lauda spent much of the opening session chatting to the sport's former commercial supremo Bernie Ecclestone, who was appearing at a race for the first time since he was shuffled aside by chairman Chase Carey and Formula One's new owners Liberty Media.
Red Bull's Max Verstappen was third and eighth fastest.
German driver Pascal Wehrlein, who missed the first two races with a back injury, returned with Sauber and was 18th and 19th in the two sessions.
McLaren's Belgian rookie Stoffel Vandoorne, who scored a point in Bahrain last year as a stand-in, stopped on track with engine problems 21 minutes from the end of the first session and was slowest in the second with only eight laps.