Nico Rosberg was fastest in after practice at the Bahrain grand prix, setting a time of 1m32.816, seven tenths quicker than the fastest of the morning session, set by Lewis Hamilton.
Rosberg's Mercedes AMG team-mate Michael Schumacher finished the 90-minute session in fifth, behind the two Red Bulls of Mark Webber and Sebastian Vettel in second and third, and Lewis Hamilton in fourth.
Following Rosberg's dominant performance in Malaysia last week - earning his and the team's first win - the team is looking strong again for the fourth round of the 2012 season.
Amid controversy and riots off the track forcing two Force India mechanics to fly back to the UK after getting caught up in violence - both Friday practice sessions went off without a hitch.
Force India took part in the morning session but chose not to run in the afternoon, as they wanted to leave the track and return to their hotel in daylight, meaning just 22 cars took part in the second stint.
Mark Webber posted a 1m33.262, some four tenths behind Rosberg, with his team-mate Vettel a further three tenths behind the Australian.
While outright performance cannot be easily judged in friday practice sessions, it remains clear that the Mercedes AMG is a credible rival to the McLaren and Red Bull.
Lewis Hamilton was fastest in morning practice, but could only manage fourth in the afternoon, just under a second behind Rosberg and half a second ahead of team-mate Jenson Button, who finished sixth, two tenths ahead of Kamui kobayashi in the Ferrari-engined Sauber.
Yet again the works Ferrari team was beaten by engine customer team Sauber, with Fernando Alonso finishing the afternoon with a 1m34.449, less than half a tenth behind Kobayashi.
Ferrari team-mate Felipe Massa posted the twelfth-fastest time, a 1m34.941, two tenths ahead of Kimi Raikkonen in thirteenth.
The third and final practice session will take place between 9-10am BST on Saturday, with qualifying from 12-1 and the race starts at 1pm BST on Sunday.
Unofficial results for second practice are below:
Pos Driver Team Time Laps 1. Nico Rosberg Mercedes 1m32.816s 35 2. Mark Webber Red Bull-Renault 1m33.262s + 0.446 26 3. Sebastian Vettel Red Bull-Renault 1m33.525s + 0.709 28 4. Lewis Hamilton McLaren-Mercedes 1m33.747s + 0.931 26 5. Michael Schumacher Mercedes 1m33.862s + 1.046 31 6. Jenson Button McLaren-Mercedes 1m34.246s + 1.430 28 7. Kamui Kobayashi Sauber-Ferrari 1m34.411s + 1.595 34 8. Fernando Alonso Ferrari 1m34.449s + 1.633 31 9. Romain Grosjean Lotus-Renault 1m34.615s + 1.799 32 10. Sergio Perez Sauber-Ferrari 1m34.893s + 2.077 34 11. Daniel Ricciardo Toro Rosso-Ferrari 1m34.895s + 2.079 29 12. Felipe Massa Ferrari 1m34.941s + 2.125 29 13. Kimi Raikkonen Lotus-Renault 1m35.183s + 2.367 33 14. Jean-Eric Vergne Toro Rosso-Ferrari 1m35.229s + 2.413 26 15. Pastor Maldonado Williams-Renault 1m35.459s + 2.643 38 16. Vitaly Petrov Caterham-Renault 1m35.913s + 3.097 32 17. Heikki Kovalainen Caterham-Renault 1m35.968s + 3.152 35 18. Bruno Senna Williams-Renault 1m36.169s + 3.353 30 19. Timo Glock Marussia-Cosworth 1m36.587s + 3.771 32 20. Charles Pic Marussia-Cosworth 1m37.803s + 4.987 33 21. Pedro de la Rosa HRT-Cosworth 1m37.812s + 4.996 28 22. Narain Karthikeyan HRT-Cosworth 1m39.649s + 6.833 27