McLaren's Lewis Hamilton set the pace in practice for the Abu Dhabi Grand Prix on Friday while double world champion Sebastian Vettel crunched into the barriers.
Vettel, returning to the Yas Marina circuit a year on from becoming Formula One's youngest champion, skidded off at turn one with more than half an hour remaining of the second floodlit session.
The Red Bull driver, who has already wrapped up his second title, was powerless to prevent Hamilton ending the day on top of the timesheets and team mate Jenson Button second in a Friday sweep for McLaren.
Hamilton's time of one minute 39.586 seconds was 0.199 faster than Button. The older Briton was quickest in the opening afternoon daylight session in 1:40.263.
Vettel's impact with the barriers was nothing to concern the team too much, particularly as the 24-year-old has three times this season crashed on Friday before taking pole position on Saturday.
Ferrari may have been more troubled when Fernando Alonso, also a double champion, then went off at the same turn and clouted the barriers with rather more force.
The Spaniard, who still ended up third fastest, also had a spin in the opening practice.
Vettel's Australian team mate Mark Webber was second on the Yas Marina timing screens in the first session but slipped to fifth as the night fell.
Some less familiar names also enjoyed a moment in the limelight in opening practice, with Robert Wickens the first Canadian to appear on track in a grand prix weekend since 1997 champion Jacques Villeneuve departed the scene in 2006.
While Wickens replaced Belgian Jerome d'Ambrosio at Virgin Racing for the first session, Frenchmen Jean-Eric Vergne and Romain Grosjean took the wheel at Toro Rosso and Renault respectively.
Wickens was 23rd out of the 24, half a second slower than team mate Timo Glock but ahead of Rubens Barrichello who failed to set a time after a problem halted his Williams.
Vergne was 11th on the timesheets, right up with Toro Rosso's regular race driver Jaime Alguersuari, while GP2 champion Grosjean marked his return to the F1 cockpit with a time quicker than Renault's Vitaly Petrov.
Vettel and Red Bull have already clinched this year's championships but the German can still claim some Formula One records.
If the champion takes pole position on Saturday he will equal the record of 14 in a single season set by Britain's Nigel Mansell in 1992.
If Vettel wins the penultimate race of the year on Sunday, he will remain on track to equal Michael Schumacher's unprecedented tally of 13 triumphs in a season.
The German said, however, that he was not thinking about such milestones.
"It will be wrong to say that I want to beat this record or that record if it is possible," he told reporters. "Then, you are thinking of the record and how to break the record. And I think you will fail if you think that way."