Lewis Hamilton paced the opening practice for the final Grand Prix of the season in Abu Dhabi.
The reigning champion set a lap time of one minute 42.869 seconds, just under four tenths of a second ahead of title rival and Mercedes team mate Nico Rosberg.
Max Verstappen was third fastest for Red Bull, one spot ahead of his team mate Daniel Ricciardo.
Sebastian Vettel was fifth fastest, ahead of Sergio Perez who split the Ferraris.
Carlos Sainz, Felipe Massa, and Marcus Ericsson completed the top 10, with Force India's Alfonso Celis - subbing for Nico Hulkenberg, just outside in 11th.
Romain Grosjean was 12th fastest for Haas, despite again battling brake issues throughout the session. He was ahead of Felipe Nasr in the second Sauber, and Esteban Gutierrez in the other Haas.
Valtteri Bottas had a quiet session in 15th, while the Renaults of Jolyon Palmer and Kevin Magnussen were 16th and 17.
The McLarens of Fernando Alonso and Jenson Button struggled all session, finishing 18th and 20th, with Manor's Pascal Wehrlein splitting them. Button's final first practice session was cut short due to energy recovery problems.
Jordan King and Daniil Kvyat - who was also sidelined early due to a puncture - completed the field.