Lewis Hamilton and McLaren took pole position for the Spanish Grand Prix by a commanding margin over shock front row man Pastor Maldonado's Williams.
In a session full of surprises, Hamilton was half a second quicker than Maldonado, who had been rapid in final practice, topped Q2, and then held provisional pole for a while.
Hamilton was the only frontrunner to do two runs in Q3, and his initial benchmark stood until first local hero Fernando Alonso in the much improved Ferrari, then the incredible Maldonado beat him.
But there was still more to come from Hamilton, who produced a 1m21.707s to give McLaren its 150th Formula 1 pole. The Briton then stopped on track on his slowing-down lap.
Just behind Maldonado, Alonso held second ahead of Lotus team-mates Romain Grosjean and Kimi Raikkonen, who again proved extremely competitive.
Both Saubers made it into Q3, with Sergio Perez going on to take sixth, but Kamui Kobayashi consigned to 10th as his car expired on the way back to the pits at the end of Q2.
Nico Rosberg was seventh after just one early run in Q3, while both Sebastian Vettel (Red Bull) and Rosberg's Mercedes team-mate Michael Schumacher chose to save tyres and not doing any flying laps in Q3, so qualified eighth and ninth.
The presence of the underdogs in the top 10 inevitably meant some big names were squeezed out in Q2, and it was Jenson Button - who had been uncomfortable with the McLaren's handling all day - and Mark Webber who found themselves on the wrong side of the cut-off. The McLaren and Red Bull will share row six, double Catalunya polesitter Webber having been sat in the pits at the end of the session as others improved and pushed him backwards.
It was a bad day for Felipe Massa as well, the Ferrari driver registering his worst grid position so far in this already-disappointing season as he qualified behind the Force Indias and Toro Rossos in 17th.
While Maldonado stormed towards the front, his Williams team-mate Bruno Senna pushed too hard in his efforts to keep up - spinning into the gravel at the end of Q1 and ensuring an instant exit.
Vitaly Petrov outqualified Caterham team-mate Heikki Kovalainen for the first time as the back-of-the-grid teams lined up in the usual order. Charles Pic was quicker than fellow Marussia man Timo Glock, and HRT's Narain Karthikeyan will needs stewards' permission to race as apparent mechanical issues left him a long way from the 107 per cent margin.
Pos Driver Team Time Gap
1. Lewis Hamilton McLaren-Mercedes 1m21.707s
2. Pastor Maldonado Williams-Renault 1m22.285s + 0.578
3. Fernando Alonso Ferrari 1m22.302s + 0.595
4. Romain Grosjean Lotus-Renault 1m22.424s + 0.717
5. Kimi Raikkonen Lotus-Renault 1m22.487s + 0.780
6. Sergio Perez Sauber-Ferrari 1m22.533s + 0.826
7. Nico Rosberg Mercedes 1m23.005s + 1.298
8. Sebastian Vettel Red Bull-Renault No time
9. Michael Schumacher Mercedes No time
10. Kamui Kobayashi Sauber-Ferrari No time
Q2 cut-off time: 1m22.904s Gap **
11. Jenson Button McLaren-Mercedes 1m22.944s + 0.839
12. Mark Webber Red Bull-Renault 1m22.977s + 0.872
13. Paul di Resta Force India-Mercedes 1m23.125s + 1.020
14. Nico Hulkenberg Force India-Mercedes 1m23.177s + 1.072
15. Jean-Eric Vergne Toro Rosso-Ferrari 1m23.265s + 1.160
16. Daniel Ricciardo Toro Rosso-Ferrari 1m23.442s + 1.337
17. Felipe Massa Ferrari 1m23.444s + 1.339
Q1 cut-off time: 1m24.362s Gap *
18. Bruno Senna Williams-Renault 1m24.981s + 2.398
19. Vitaly Petrov Caterham-Renault 1m25.277s + 2.694
20. Heikki Kovalainen Caterham-Renault 1m25.507s + 2.924
21. Charles Pic Marussia-Cosworth 1m26.582s + 3.999
22. Timo Glock Marussia-Cosworth 1m27.032s + 4.449
23. Pedro de la Rosa HRT-Cosworth 1m27.555s + 4.972
24. Narain Karthikeyan HRT-Cosworth 1m31.122s + 8.539
107% time: 1m28.363s
* Gap to quickest in Q1
** Gap to quickest in Q2