Romain Grosjean topped the times for troubled Lotus in Friday morning's opening free practice session ahead of this weekend's Abu Dhabi Grand Prix.
The 27-year-old Frenchman delivered a late fastest lap of one minute and 44.241 seconds at the Yas Marina Circuit to outpace nearest rival Briton Lewis Hamilton of Mercedes by 0.19 seconds.
Newly-crowned quadruple world champion Sebastian Vettel was third ahead of his Red Bull team-mate Australian Mark Webber.
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Hamilton's Mercedes team-mate Nico Rosberg was fifth fastest ahead of late arrival Kimi Raikkonen in the second Lotus, Briton Paul Di Resta of Force India and Jenson Button of McLaren.
Venezuelan Pastor Maldonado was ninth for Williams and Mexican Sergio Perez 10th in the second McLaren.
It was the first time this season that Grosjean or Lotus had topped the times in opening practice, but came after the team had been at the centre of a controversy on Thursday when Raikkonen failed to turn up at the track for his media commitments.
Raikkonen, who has made clear that he has not been paid his full salary by Lotus this year, was involved in a heated exchange of profanities with the team during last Sunday's Indian Grand Prix. He will join Ferrari next season.
The Lotus team have not yet secured a replacement driver amid speculation that they need to sign a driver with a big sponsorship package.