Championship leader Sebastian Vettel clocked the fastest time for Ferrari in Friday's opening free practice session for this weekend's Bahrain Grand Prix.
The four-time world champion recorded a best lap in one minute and 32.697 seconds to wind up four-tenths of a second ahead of Australian Daniel Ricciardo of Red Bull.
Ricciardo's Red Bull team-mate Max Verstappen was third ahead of Sergio Perez of Force India and Felipe Massa of Williams.
Three-time champion Lewis Hamilton, who shares the leadership of this year's embryonic title race with Vettel, was down in 10th for Mercedes, the champion team not attempting to deliver their best in scorching hot conditions.
His new Mercedes team-mate Valtteri Bottas was 14th quickest as they went about their own programme of preparation in temperatures that touched 48 degrees Celsius.
Fellow-Finn Kimi Raikkonen in the second Ferrari suffered a blazing engine failure midway through the 90-minutes action and had to park his car off-track before walking back towards the pits.
In the hot, dry and dusty conditions at the Bahrain International Circuit, the outcome was not representative of true potential for Sunday's race when the temperature is expected to be cooler by at least 15 degrees.
Many of the drivers complained of lack of grip as demonstrated by several spins, including one spectacular off-circuit excursion by Massa in the closing stages.
Vettel's fastest lap was more than four-tenths of a second slower than 2016 world champion Nico Rosberg's fastest at last year's event.
It was more than two seconds adrift of the record set by seven-time champion Michael Schumacher for Ferrari in 2004 when he lapped in 1:30.252.