Valtteri Bottas edged out new temporary team-mate George Russell as Mercedes impressively locked out the front row at the Sakhir Grand Prix despite the absence of Lewis Hamilton.
Williams driver Russell is standing in for seven-time world champion Hamilton, who has tested positive for coronavirus.
And after impressing in Friday's practice, Russell was strong again in qualifying on Saturday, pushing Bottas to the limit as the Finn claimed pole by a margin of just 0.026 seconds.
Max Verstappen was close behind in third, with Charles Leclerc taking a strong fourth place for Ferrari.
Racing Point's Sergio Perez will start fifth on the grid, while the second Red Bull of Alex Albon qualified down in 12th after missing out on a place in Q3.
Verstappen and Leclerc set the fastest initial times in the third qualifying session in a race weekend which is being held on a different, shorter track configuration to the one used for the Bahrain Grand Prix last week, when Hamilton claimed a fifth straight victory.
But Mercedes' opening runs had taken place on used tyres and they soon upped the pace on fresh rubber, with a time of 53.377s on Bahrain's fast Outer loop enough to see Bottas pip Russell to top spot.
Earlier, Bottas was quickest in the first session while Verstappen was fastest in the second, as Esteban Ocon, Sebastian Vettel and Lando Norris were among those to suffer elimination with Albon.
Verstappen was only 0.056s behind the pole pace and will hope to be a thorn in Mercedes' side in Sunday's race.
The pressure will be on Bottas to keep his less-experienced colleague Russell, who is expected to drive for the team permanently in the future, behind him, with all eyes on how the Mercedes debutant fares in Formula One's quickest car.
Daniil Kvyat impressively finished sixth for AlphaTauri, who also had Pierre Gasly in ninth position.
1. Valtteri Bottas (Mercedes) 53.377s
2. George Russell (Mercedes) +0.026s
3. Max Verstappen (Red Bull) +0.056s
4. Charles Leclerc (Ferrari) +0.236s
5. Sergio Perez (Racing Point) +0.413s
6. Daniil Kvyat (AlphaTauri) +0.529s
7. Daniel Ricciardo (Renault) +0.580s
8. Carlos Sainz (McLaren) +0.633s
9. Pierre Gasly (AlphaTauri) +0.777s
10. Lance Stroll (Racing Point) +0.823s