Kubica set the fastest time in final free practice on Saturday

Kubica lapped the Albert Park circuit on Saturday in one minute 25.613 seconds, with Heidfeld 0.337 slower.

Fernando Alonso was third for Renault in a low-key session for favourites Ferrari and McLaren.

World champion Kimi Raikkonen, last year's winner in Melbourne, was 14th while Lewis Hamilton was 12th.

Germany's Nico Rosberg, who was sidelined for much of Friday because of a gearbox problem, completed 17 laps on a warm morning and was fourth fastest ahead of the Red Bulls of David Coulthard and Mark Webber.

Despite posting the quickest time on Friday, his 1:26.461 in the first session, Ferrari's Raikkonen said he was unhappy with his car set up.

On Saturday morning, he drove off the track at turn one halfway through the session and only completed 17 laps.

His team-mate Felipe Massa completed 19 laps and was 11th in the third session, while McLaren's Heikki Kovalainen was third-to-last.

Final practice times from Australian Grand Prix at Albert Park, Melbourne:

1. Robert Kubica (Poland) BMW Sauber 1:25.613
2. Nick Heidfeld (Germany) BMW Sauber 1:25.950
3. Fernando Alonso (Spain) Renault 1:26.082
4. Nico Rosberg (Germany) Williams - Toyota 1:26.171
5. David Coulthard (Britain) RedBull - Renault 1:26.385
6. Mark Webber (Australia) RedBull - Renault 1:26.407
7. Jenson Button (Britain) Honda 1:26.502
8. Sebastian Vettel (Germany) Toro Rosso - Ferrari 1:26.663
9. Giancarlo Fisichella (Italy) Force India - Ferrari 1:26.682
10. Jarno Trulli (Italy) Toyota 1:26.882
11. Felipe Massa (Brazil) Ferrari 1:27.020
12. Lewis Hamilton (Britain) McLaren 1:27.084
13. Timo Glock (Germany) Toyota 1:27.162
14. Kimi Raikkonen (Finland) Ferrari 1:27.163
15. Nelsinho Piquet (Brazil) Renault 1:27.284
16. Rubens Barrichello (Brazil) Honda 1:27.333
17. Adrian Sutil (Germany) Force India - Ferrari 1:27.489
18. Sebastien Bourdais (France) Toro Rosso - Ferrari 1:27.578
19. Kazuki Nakajima (Japan) Williams - Toyota 1:27.601
20. Heikki Kovalainen (Finland) McLaren 1:27.992
21. Takuma Sato (Japan) Super Aguri - Honda 1:28.363
22. Anthony Davidson (Britain) Super Aguri - Honda 1:28.912

Follow live coverage of the Australian Grand Prix on 5 Live and bbc.co.uk/sport. Qualifying starts at 0300 GMT on Saturday with the race at 0430 on Sunday.