Adrian Sutil surprised onlookers by setting the fastest time in an interrupted final free practice session in Valencia.
The German set the fastest time of the weekend - a 1m39.143s - on his final lap of the session, having survived a late attack from Kazuki Nakajima, Robert Kubica and Heikki Kovalainen.
The Force India driver had been quickest just before the session was red-flagged after 28 minutes to clear away Sebastian Vettel's Red Bull, which suffered a major mechanical failure on the track.
The RB5 left significant amounts of debris and oil on the third sector of the track and it took circuit officials another 28 minutes to make the track usable again.
The amount of cement dust laid down hindered those drivers that tried to improve when the track was reopened in the final four minutes of the session, and it was only on their final laps that the order changed at the top.
Until then, world champion Lewis Hamilton had been setting the pace on a track that had already collected quite a lot of dust overnight.
The McLaren driver, who missed a large part of yesterday's afternoon session after damaging his car, worked through a number of increasingly fast laps until he set his best of 1m39.950s after 20 minutes.
Behind him, Sutil, Nico Rosberg, Jenson Button, Romain Grosjean and Kubica had squabbled over second place.
That was until Sutil, whose Force India has looked strong all weekend, went quickest of all on a 1m39.897s, just before Vettel's engine apparently failed.
In the final four minutes, Sutil dropped to fourth on the order before bouncing back with his final flier.
Nakajima took second ahead of Kubica, Kovalainen, Rosberg and Giancarlo Fisichella in the second Force India.
Button was seventh, Hamilton eighth and Jarno Trulli and Grosjean - who was quickest at one point early on - completed the top ten.
Ferrari's Luca Badoer ended the session last - 3.055 seconds away from Sutil's time.
Pos Driver Team Time Laps
1. Sutil Force India-Mercedes (B) 1:39.143 12
2. Nakajima Williams-Toyota (B) 1:39.247 + 0.104 12
3. Kubica BMW Sauber (B) 1:39.513 + 0.370 12
4. Kovalainen McLaren-Mercedes (B) 1:39.553 + 0.410 8
5. Rosberg Williams-Toyota (B) 1:39.732 + 0.589 11
6. Fisichella Force India-Mercedes (B) 1:39.764 + 0.621 12
7. Button Brawn GP-Mercedes (B) 1:39.883 + 0.740 10
8. Hamilton McLaren-Mercedes (B) 1:39.950 + 0.807 12
9. Trulli Toyota (B) 1:40.017 + 0.874 11
10. Grosjean Renault (B) 1:40.088 + 0.945 11
11. Buemi Toro Rosso-Ferrari (B) 1:40.118 + 0.975 12
12. Barrichello Brawn GP-Mercedes (B) 1:40.192 + 1.049 10
13. Heidfeld BMW Sauber (B) 1:40.230 + 1.087 12
14. Raikkonen Ferrari (B) 1:40.260 + 1.117 12
15. Alonso Renault (B) 1:40.402 + 1.259 9
16. Glock Toyota (B) 1:40.443 + 1.300 10
17. Webber Red Bull-Renault (B) 1:40.879 + 1.736 10
18. Vettel Red Bull-Renault (B) 1:40.916 + 1.773 6
19. Alguersuari Toro Rosso-Ferrari (B) 1:41.125 + 1.982 12
20. Badoer Ferrari (B) 1:42.198 + 3.055 14
All timing unofficial