Rosberg pipped reigning world champion Sebastian Vettel for Red Bull and Fernando Alonso in his Ferrari to claim only the second pole of his 132-race career for Sunday's Bahrain Grand Prix.
It is the first time since last year's race in China the 27-year-old will lead away the field, and the first time this season he has out-qualified team-mate Lewis Hamilton.
Hamilton set the fourth fastest time, but a five-place penalty for a gearbox change ahead of qualifying at the Bahrain International Circuit means he now falls to ninth. Hamilton was on pole last week in Shanghai, but even with the penalty has so far struggled this weekend at the desert-based Sakhir track.
Red Bull's Mark Webber was fifth quickest, but like Hamilton, faces a penalty of three places after colliding with the Toro Rosso of Jean-Eric Vergne last weekend.
It means Felipe Massa will move up to fourth in his Ferrari, with the Force Indias of Paul Di Resta and Adrian Sutil lining up fifth and sixth. Then comes Webber, who actually only loses two places courtesy of Hamilton, followed by Kimi Raikkonen in his Lotus who moves from ninth to eighth.
Alongside Hamilton on the fifth row will be former team-mate Jenson Button in his McLaren. In 11th and 12th, after dropping out in Q2 will be Romain Grosjean in his Lotus and McLaren's Sergio Perez, beaten by team-mates Raikkonen and Button respectively for the fourth straight race.
Toro Rosso's Daniel Ricciardo, who a week ago in China qualified seventh, will start 13th, with team-mate Jean-Eric Vergne 16th. Sandwiched in between the pair are Sauber's Nico Hulkenberg and the Williams of Valtteri Bottas. In a remarkable twist at the end of the opening 20-minute Q1 session, Pastor Maldonado dropped out after setting the same time as Williams team-mate Bottas.
Maldonado will start 17th ahead of Sauber's Esteban Gutierrez, with the Mexican out-qualified by Hulkenberg for the fourth consecutive race, and failing to make it into Q2 for the third time.
With a five-place grid penalty to serve for the race after running into the back of Sutil in Shanghai, Gutierrez will start at the back of the grid. Caterham and Marussia naturally share the bottom four places, with Charles Pic a season's best of 19th since switching from the latter to the former for this season. Either side of Caterham's Giedo van der Garde are Marussia duo Jules Bianchi and Max Chilton, with the 21-year-old Briton setting the slowest time in qualifying for the first time this year.
Bahrain Grand Prix Qualifying Grid
1. Nico Rosberg (Mercedes)
2. Sebastian Vettel (Red Bull)
3. Fernando Alonso (Ferrari)
4. Felipe Massa (Ferrari)
5. Paul di Resta (Force India)
6. Adrian Sutil (Force India)
7. Mark Webber (Red Bull)
8. Kimi Raikkonen (Lotus)
9. Lewis Hamilton (Mercedes)
10. Jenson Button (McLaren)
11. Romain Grosjean (Lotus)
12. Sergio Perez (McLaren)
13. Daniel Ricciardo (Toro Rosso)
14. Nico Hulkenberg (Sauber)
15. Valtteri Bottas (Williams)
16. Jean-Eric Vergne (Toro Rosso)
17. Pastor Maldonado (Williams)
18. Charles Pic (Caterham)
19. Jules Bianchi (Marussia)
20. Giedo van der Garde (Caterham)
21. Max Chilton (Marussia)
22. Esteban Gutierrez (Sauber)
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