Great Britain's 2008 Fomula One world champion Lewis Hamilton clocked the fastest time during the second day of testing Wednesday at the Sakhir circuit where he won the Bahrain Grand Prix at the weekend.
Three of the five world champions still competing -- England's Jenson Button (McLaren), Finland's Kimi Raikkonen (Ferrari) and Germany's Sebastian Vettel (Red Bull) -- did not take part in the testing which allowed certain stables to use their reserve drivers and Pirelli to test their new tyres.
"It's been a long day, running lap after lap to analyse the tyres but driving a Formula One car is never boring," said Hamilton, who clocked a fastest lap of 1min 34.136sec after 132 laps.
"Of course, the nature of a tyre test means we haven't learnt anything in particular in terms of improving the car but it's useful for Pirelli and therefore useful to us in the long term.
"They just gave me different sets and I told them how each felt. The plan was just to get in as many laps as we could. The times mean nothing as everyone had their own programmes to run.
"It's been a fantastic few weeks for the team but also a long stint away, so I'm sure everyone is looking forward to heading back home for a well-deserved rest.
"It's a short turnaround before China so I'll be in the factory to work on ways we can improve."
Hamilton's Mercedes teammate and championship leader Nico Rosberg clocked the fastest time in the day's first practice session.
Other two-day practice sessions will take place throughout the season, on the Tuesday and Wednesday, after certain Grand Prix.
The fourth race of the 2014 Formula One season, the Chinese Grand Prix, takes place on April 20.
1. Lewis Hamilton (GBR/Mercedes) 1min 34.136sec (120 laps), 2. Jean-Eric Vergne (FRA/Toro Rosso-Renault) 1:35.557 (63), 3. Kevin Magnussen (DEN/McLaren-Mercedes) 1:36.203 (26), 4. Sergio Perez (MEX/Force India-Mercedes) 1:36.586 (62), 5. Daniel Ricciardo (AUS/Red Bull-Renault) 1:37.310 (65), 6. Jules Bianchi (FRA/Marussia-Ferrari) 1:37.316 (93), 7. Giedo van der Garde (NED/Sauber-Ferrari) 1:37.623 (77), 8. Fernando Alonso (ESP/Ferrari) 1:39.912 (12), 9. Marcus Ericsson (SWE/Caterham-Renault) 1:39.263 (66), 10. Felipe Nasr (BRA/Williams-Mercedes) 1:39.679 (64), 11. Romain Grosjean (FRA/Lotus-Renault) 1:40.183 (16)