Lewis Hamilton headed Jenson Button as McLaren dominated the first free practice session for the Abu Dhabi Grand Prix on Friday morning.
Hamilton set his table-topping 1m43.285s lap with 25 of the 90 minutes remaining, and beat his countryman and team-mate by 0.333s, with title protagonists Sebastian Vettel and Fernando Alonso third and fourth.
More than 35 minutes had elapsed when most of the drivers took to the track, surface temperatures having exceeded 45 degrees Celsius by that point.
Jean-Eric Vergne set the initial pace, and brought his marker down from 1m48.9s to 1m46.6s before Valtteri Bottas, Michael Schumacher and Alonso took turns at the top, the latter in 1m45.1s with 50 minutes gone.
Championship leader Vettel was the first driver to break into the 1m44s shortly afterwards, but his spell at the top lasted less than a minute as Hamilton took a lead he would not relinquish.
Button improved his time before the end of the session as Hamilton experimented with a number of different fuel settings during the final half-hour.
Vettel ended up third, despite the double world champion running wide at Turn 16 after getting his Red Bull crossed up on the kerb at the corner's entry.
Ferrari driver Alonso, who had dropped to sixth, set his best time in the final minute of the session to climb back up to fourth, ahead of Mark Webber in the second Red Bull and Michael Schumacher's Mercedes.
Pastor Maldonado and Nico Rosberg completed the top eight while Bottas was the best of the test drivers in action in his Williams. He was ninth overall, ahead of Kimi Raikkonen's Lotus.
Sauber driver Sergio Perez had a scary moment at the pit entrance with 12 minutes to go. Attempting to simulate a full-speed, race entry, the Mexican ran wide as he turned right and was forced to drive over the run-off area and back onto the race track to avoid contact with the barrier.
Heikki Kovalainen was the only one of the Caterham drivers to set a time as Giedo van der Garde spent the session in the garage as his team tried to rectify an engine installation issue.
Marussia's Max Chilton did get out though, to undertake a series of aero tests in his maiden F1 practice outing.
His team-mate Timo Glock, 20th, suffered a series of lock-ups and wide moments. He lost a potentially strong laptime with 25 minutes left when he was impeded by Schumacher's Mercedes under braking for the left-hander at the end of the main straight.
He communicated his annoyance with a waved hand, but immediately saw Schumacher pull off the track and gesturing a wave of his own in the Marussia's direction by way of apology.
Pos Driver Team Time Laps 1. Lewis Hamilton McLaren-Mercedes 1m43.285 20 2. Jenson Button McLaren-Mercedes 1m43.618s + 0.333 18 3. Sebastian Vettel Red Bull-Renault 1m44.050s + 0.765 21 4. Fernando Alonso Ferrari 1m44.366s + 1.081 20 5. Mark Webber Red Bull-Renault 1m44.542s + 1.257 21 6. Michael Schumacher Mercedes 1m44.694s + 1.409 21 7. Nico Rosberg Mercedes 1m45.194s + 1.909 19 8. Pastor Maldonado Williams-Renault 1m45.347s + 2.062 24 9. Valtteri Bottas Williams-Renault 1m45.347s + 2.062 23 10. Kimi Raikkonen Lotus-Renault 1m45.422s + 2.137 15 11. Felipe Massa Ferrari 1m45.567s + 2.282 23 12. Nico Hulkenberg Force India-Mercedes 1m45.587s + 2.302 18 13. Kamui Kobayashi Sauber-Ferrari 1m45.722s + 2.437 19 14. Romain Grosjean Lotus-Renault 1m45.743s + 2.458 19 15. Jules Bianchi Force India-Mercedes 1m45.769s + 2.484 21 16. Sergio Perez Sauber-Ferrari 1m45.811s + 2.526 21 17. Daniel Ricciardo Toro Rosso-Ferrari 1m46.649s + 3.364 22 18. Jean-Eric Vergne Toro Rosso-Ferrari 1m46.708s + 3.423 24 19. Heikki Kovalainen Caterham-Renault 1m47.418s + 4.133 22 20. Timo Glock Marussia-Cosworth 1m47.891s + 4.606 19 21. Pedro de la Rosa HRT-Cosworth 1m48.354s + 5.069 21 22. Max Chilton Marussia-Cosworth 1m48.887s + 5.602 21 23. Ma Qing Hua HRT-Cosworth 1m50.487s + 7.202 20 24. Giedo van der Garde Caterham-Renault no time 3 All Timing Unofficial