Felipe Massa emerged quickest from a late scramble on a drying track in second practice for the British Grand Prix at Silverstone.
With very heavy rain falling on the eve of the session getting under way, the sodden fans had little to watch for the first half of the afternoon, with only four midfield cars venturing out for exploratory installation laps.
It was 51 minutes into the session before Toro Rosso's Jaime Alguersuari became the first man to try a flying lap. He spent a while swapping the top spot with the likes of his teammate Sebastien Buemi, Mercedes' Michael Schumacher and Force India's Adrian Sutil, before morning pacesetter Mark Webber went back to the front for Red Bull.
But the rate of improvement as the weather finally improved was such that Webber ultimately fell right back to 14th, while Schumacher – who went back ahead with only a few minutes to go – tumbled to 12th. World Championship leader Sebastian Vettel sat out the best of the conditions and was only 18th in the other Red Bull.
Massa then produced a 1m49.967s for Ferrari to take the top spot just as the session finished, deposing Mercedes' Nico Rosberg by 0.777sec.
Sauber repaired Kamui Kobayashi's car following his massive morning accident and he took third, ahead of McLaren duo Lewis Hamilton and Jenson Button, with Sutil sixth.
The changing conditions allowed a few upsets, with Heikki Kovalainen 13th fastest for Lotus, Fernando Alonso back in 15th in the other Ferrari, and new signing Daniel Ricciardo edging ahead of Hispania teammate Tonio Liuzzi at the foot of the order.
Pos Driver Team Time Laps
1. Felipe Massa Ferrari 1m49.967s 9
2. Nico Rosberg Mercedes 1m50.744s + 0.777 16
3. Kamui Kobayashi Sauber-Ferrari 1m51.395s + 1.428 16
4. Lewis Hamilton McLaren-Mercedes 1m51.438s + 1.471 6
5. Jenson Button McLaren-Mercedes 1m51.518s + 1.551 6
6. Adrian Sutil Force India-Mercedes 1m51.738s + 1.771 18
7. Paul di Resta Force India-Mercedes 1m51.781s + 1.814 7
8. Rubens Barrichello Williams-Cosworth 1m51.992s + 2.025 13
9. Sergio Perez Sauber-Ferrari 1m52.169s + 2.202 12
10. Sebastien Buemi Toro Rosso-Ferrari 1m52.189s + 2.222 21
11. Vitaly Petrov Renault 1m52.198s + 2.231 9
12. Michael Schumacher Mercedes 1m52.325s + 2.358 12
13. Heikki Kovalainen Lotus-Renault 1m52.578s + 2.611 16
14. Mark Webber Red Bull-Renault 1m52.587s + 2.620 6
15. Fernando Alonso Ferrari 1m52.869s + 2.902 8
16. Nick Heidfeld Renault 1m54.023s + 4.056 8
17. Jaime Alguersuari Toro Rosso-Ferrari 1m54.274s + 4.307 16
18. Sebastian Vettel Red Bull-Renault 1m54.545s + 4.578 4
19. Jerome D'Ambrosio Virgin-Cosworth 1m54.714s + 4.747 13
20. Pastor Maldonado Williams-Cosworth 1m55.155s + 5.188 8
21. Jarno Trulli Lotus-Renault 1m55.155s + 5.188 12
22. Timo Glock Virgin-Cosworth 1m55.549s + 5.582 10
23. Daniel Ricciardo HRT-Cosworth 1m55.828s + 5.861 10
24. Tonio Liuzzi HRT-Cosworth 1m56.037s + 6.070 6
All Timing Unofficial