Lewis Hamilton set the fastest time in the opening free practice session for the Bahrain Grand Prix ahead of world champion Sebastian Vettel's Red Bull and Paul di Resta's Force India.
In a fairly uneventful 90 minutes of running, the McLaren driver set a time of 1m33.572s in the middle of the session and remained unchallenged thereafter.
As expected, the teams were greeted with warm track temperatures - 27 degrees C and rising - but just as predictable was the surface layer of sand on the asphalt that prompted one team to dismissively say the morning's runs as nothing more than 'dust surveys'. It led to a slow start to the morning.
Nico Hulkenberg was the first driver to set a time, a 1m35.544s lap, 20 minutes in. Dicing with his Force India team-mate di Resta, who also moved to the top during this period, the German then improved that to a 1m34.859s.
Other early runners were Romain Grosjean and Sauber's Kamui Kobayashi, who like Caterham's Heikki Kovalainen before him, ran too hot into the tightening Turn 10 left-hander and ran over the sand-coloured painted run-off. There would be several more cases of this through the field.
By one third's distance Grosjean's Lotus, complete with a new front wing for this race, had moved to the top of the times with a 1m34.847s. The Frenchman looked fairly wild though as he explored the limits of the track.
Not long after that, Lotus's Kimi Raikkonen set a new benchmark, the Finn lowering the target to a 1m34.609s on the revised-back-to-its-original Sakhir layout.
Just before half distance the Red Bulls emerged from the pits for their first runs on the Pirelli medium primes and immediately Vettel went fastest with a 1m34.311s - the German now using the newer exhaust layout that Mark Webber chose to run in Shanghai.
But if his first lap was impressive, he followed it up with a much faster 1m33.877s, setting three purple sector times as he did so. His team-mate on the hand could only manage third fastest, having locked up on his early quick lap.
The two Mercedes were also out at the same time for their early runs on the prime tyres, but neither Nico Rosberg nor Michael Schumacher could match that Vettel time at this stage and went second and third quickest, while Jenson Button in the McLaren, went fourth.
Just before the hour mark world championship leader Hamilton moved to the top with a 1m33.572s - three tenths up on Vettel - as Rosberg and Button also improved to third and fourth, ahead of Schumacher.
Things settled down for a while after that as teams continued working through their programmes on the prime sets they'd hand back after the morning session was over.
During this period di Resta's KERS went intermittent and he was forced to switch it off, running wide at the final corner not long after that.
Despite the track being less dusty, to the surprise of the teams, few of them seemed keen to chase times massively.
But in the last 10 minutes of the session both the Force Indias made the surprising decision to make an early switch to the option tyre, which explained why di Resta jumped up to third late on and Hulkenberg ended up sixth.
Neither Ferrari made it into the top ten after a low profile session that ended with Fernando Alonso 13th and Felipe Massa 15th - split by Valtteri Bottas's Williams.
Pos Driver Team Time Laps 1. Lewis Hamilton McLaren-Mercedes 1m33.572 11 2. Sebastian Vettel Red Bull-Renault 1m33.877s + 0.305 21 3. Paul di Resta Force India-Mercedes 1m34.150s + 0.578 26 4. Nico Rosberg Mercedes 1m34.249s + 0.677 23 5. Jenson Button McLaren-Mercedes 1m34.277s + 0.705 14 6. Nico Hulkenberg Force India-Mercedes 1m34.344s + 0.772 26 7. Michael Schumacher Mercedes 1m34.483s + 0.911 17 8. Mark Webber Red Bull-Renault 1m34.552s + 0.980 22 9. Kimi Raikkonen Lotus-Renault 1m34.609s + 1.037 17 10. Romain Grosjean Lotus-Renault 1m34.847s + 1.275 20 11. Sergio Perez Sauber-Ferrari 1m35.024s + 1.452 22 12. Pastor Maldonado Williams-Renault 1m35.268s + 1.696 24 13. Fernando Alonso Ferrari 1m35.436s + 1.864 21 14. Valtteri Bottas Williams-Renault 1m35.497s + 1.925 24 15. Felipe Massa Ferrari 1m35.719s + 2.147 19 16. Kamui Kobayashi Sauber-Ferrari 1m35.929s + 2.357 24 17. Jean-Eric Vergne Toro Rosso-Ferrari 1m36.195s + 2.623 20 18. Heikki Kovalainen Caterham-Renault 1m36.330s + 2.758 11 19. Vitaly Petrov Caterham-Renault 1m36.484s + 2.912 18 20. Daniel Ricciardo Toro Rosso-Ferrari 1m36.591s + 3.019 20 21. Charles Pic Marussia-Cosworth 1m37.467s + 3.895 17 22. Timo Glock Marussia-Cosworth 1m38.006s + 4.434 18 23. Pedro de la Rosa HRT-Cosworth 1m38.877s + 5.305 19 24. Narain Karthikeyan HRT-Cosworth 1m39.996s + 6.424 23 All Timing Unofficial