Sebastian Vettel fired a clear message to his Red Bull teammate Mark Webber as he set the fastest time on his final lap of Saturday morning's practice session, with a time of 1m15.103s.
The German's lap was an immediate response to that of Webber, who had set a lap 0.6s slower moments prior to that. Splitting them to go second overall however was Fernando Alonso, whose own lap was only 0.284s slower than Vettel at the flag.
Ferrari and Red Bull went at it again for much of the 'serious running' toward the end of the hour as the two teams dominated the action.
The session had begun wet following intermittent rain, but by halfway through, the field was finally presented with a more or less dry circuit with which to hurriedly work on a qualifying setup.
For the next 20 minutes much of the grid ran on the hard prime tyres as they sought balance, and it was Jenson Button that proved fastest through that phase with a 1m18.576s.
But that was until Vettel and Alonso emerged from the pits with 10 minutes to go, their cars shod in super-soft option Bridgestones – and the Ferrari driver lowered the mark to 1m16.805s. This inevitably triggered a frenzy of activity as virtually the entire entry list followed suit.
In the end, as the times fell out, it was Felipe Massa that completed the top four, behind the three mentioned above, ahead of Nico Rosberg, with Lewis Hamilton ending the fastest McLaren driver in sixth.
Michael Schumacher, one of many to go off at the wet Turn 6 hairpin earlier in the session, was seventh in the second Mercedes, while Rubens Barrichello, Robert Kubica and Nico Hulkenberg completed the top ten.
Button drifted back to 13th, while Adrian Sutil (fastest on Friday morning) was forced to trickle back to the pits early on with a broken driveshaft.
The German's forced absence meant that all the new teams, lead by the Lotus cars of Jarno Trulli and Heikki Kovalainen ended a place higher on the time sheets than usual.
Pos Driver Team Time Laps
1. Vettel Red Bull-Renault 1:15.103 18
2. Alonso Ferrari 1:15.387 + 0.284 21
3. Webber Red Bull-Renault 1:15.708 + 0.605 16
4. Massa Ferrari 1:15.854 + 0.751 20
5. Rosberg Mercedes 1:16.046 + 0.943 20
6. Hamilton McLaren-Mercedes 1:16.207 + 1.104 13
7. Schumacher Mercedes 1:16.473 + 1.370 16
8. Barrichello Williams-Cosworth 1:16.481 + 1.378 23
9. Kubica Renault 1:16.646 + 1.543 20
10. Hulkenberg Williams-Cosworth 1:16.743 + 1.640 17
11. Kobayashi Sauber-Ferrari 1:16.882 + 1.779 19
12. Buemi Toro Rosso-Ferrari 1:16.990 + 1.887 21
13. Button McLaren-Mercedes 1:17.037 + 1.934 15
14. Petrov Renault 1:17.148 + 2.045 20
15. de la Rosa Sauber-Ferrari 1:17.220 + 2.117 19
16. Alguersuari Toro Rosso-Ferrari 1:17.341 + 2.238 21
17. Liuzzi Force India-Mercedes 1:17.538 + 2.435 22
18. Kovalainen Lotus-Cosworth 1:19.193 + 4.090 11
19. Trulli Lotus-Cosworth 1:19.607 + 4.504 10
20. Senna HRT-Cosworth 1:20.533 + 5.430 9
21. Yamamoto HRT-Cosworth 1:21.538 + 6.435 14
22. di Grassi Virgin-Cosworth 1:23.444 + 8.341 10
23. Glock Virgin-Cosworth 1:23.873 + 8.770 7
24. Sutil Force India-Mercedes 2
All Timing Unofficial