Romain Grosjean put Lotus on top of the times in final practice for the Australian Grand Prix as the rain hit the Albert Park circuit and Sebastian Vettel hit trouble.
Grosjean posted a best time of 1m26.929s right before the heavens opened and that kept the Frenchman ahead of his rivals until the end.
Ferrari's Fernando Alonso and team-mate Felipe Massa were second and third ahead of Force India's Paul di Resta and Grosjean's team-mate Kimi Raikkonen.
Red Bull driver Vettel finished down in 12th after stopping on track late in the session.
With rain threatening to hit the session early on, the majority of drivers began completing full laps right away, with Mark Webber the first frontrunner to set a time.
The Australian was quickly outpaced by several drivers as the threat of rain increased, Brazilian Massa setting a time of 1m27.407s to move to the top 10 minutes into the session on a very busy track.
Team-mate Alonso and then Lotus's Grosjean lowered the benchmark moments later, the Frenchman posting the first 1m26 just before the rain made its appearance with 43 minutes to go.
The heavy rainstorm put an end to all the action for several minutes.
With 25 minutes to go, Massa was the first man to brave the conditions in the Ferrari, shod with full wets. With the track still very wet but with no rain, all drivers except Vettel and Jenson Button ventured out in the following minutes.
Friday's pacesetter Vettel jumped onto the track with less than 15 minutes to go, the Red Bull driver the first man to use the intermediate tyres.
His run, however, did not last long as he stopped on track with 10 minutes to go with an apparent hydraulic problem. The German managed just nine laps.
Although there was no more rain, no driver put on slicks before the end of the session and therefore there were no improvements over the times set early on.
Despite the tricky conditions and some minor scares, the session was mostly trouble-free.
Pos Driver Team Time Gap Laps
1. Romain Grosjean Lotus Renault 1m26.929s 14
2. Fernando Alonso Ferrari 1m27.000s + 0.071s 7
3. Felipe Massa Ferrari 1m27.241s + 0.312s 10
4. Paul di Resta Force India-Mercedes 1m27.533s + 0.604s 9
5. Kimi Raikkonen Lotus-Renault 1m27.625s + 0.696s 12
6. Daniel Ricciardo Toro Rosso-Ferrari 1m27.849s + 0.920s 19
7. Jean-Eric Vergne Toro Rosso-Ferrari 1m27.860s + 0.931s 16
8. Adrian Sutil Force India-Mercedes 1m28.069s + 1.140s 15
9. Nico Hulkenberg Sauber-Ferrari 1m28.253s + 1.324s 18
10. Esteban Gutierrez Sauber-Ferrari 1m28.253s + 1.324s 20
11. Nico Rosberg Mercedes 1m28.486s + 1.557s 13
12. Sebastian Vettel Red Bull-Renault 1m29.808s + 2.879s 9
13. Mark Webber Red Bull-Renault 1m30.073s + 3.144s 16
14. Jules Bianchi Marussia-Cosworth 1m30.388s + 3.459s 17
15. Giedo van der Garde Caterham-Renault 1m30.598s + 3.669s 20
16. Charles Pic Caterham-Renault 1m30.959s + 4.030s 19
17. Jenson Button McLaren-Mercedes 1m33.236s + 6.307s 7
18. Sergio Perez McLaren-Mercedes 1m33.527s + 6.598s 8
19. Pastor Maldonado Williams-Renault 1m39.232s + 12.303s 13
20. Valtteri Bottas Williams-Renault 1m39.779s + 12.850s 13
21. Max Chilton Marussia-Cosworth 1m42.872s + 15.943s 13
22. Lewis Hamilton Mercedes 1m47.246s + 20.317s 9