 Heidfeld was almost a second ahead of his team-mate Villeneuve |
Nick Heidfeld laid down a marker before qualifying for the Australian Grand Prix by setting the fastest time in morning practice. The German led home a BMW-Sauber one-two, with team-mate Jacques Villeneuve in second.
However, lap times were significantly slower than Friday due to a damp track after morning rain at Albert Park.
Vitantonio Liuzzi was third for Scuderia Toro Rosso but world champion Fernando Alonso was down in 17th.
His Renault team-mate Giancarlo Fisichella fared better in fourth, one place ahead of Toyota's Ralf Schumacher.
Jenson Button ended the one-hour session in 13th for Honda, just ahead of Red Bull man David Coulthard.
The opening minutes of the session saw Ferrari's Felipe Massa and Super Aguri's Yuji Ide spin harmlessly.
Juan Pablo Montoya and Fisichella slithered through the gravel before more rain soaked the track.
That gave Alonso a scary moment when he was caught out by the lack of grip and bounced off track and perilously close to a wall before resuming tentatively.
Button joined the club by spinning backwards across the kerbs as he grappled with the conditions, a move repeated by Red Bull's Christian Klien.
Second free practice times
1. Nick Heidfeld (Ger) BMW Sauber 1:35.335
2. Jacques Villeneuve (Can) BMW Sauber 1:36.281
3. Vitantonio Liuzzi (Ita) Toro Rosso - Cosworth 1:36.373
4. Giancarlo Fisichella (Ita) Renault 1:36.414
5. Ralf Schumacher (Ger) Toyota 1:36.445
6. Felipe Massa (Bra) Ferrari 1:36.506
7. Michael Schumacher (Ger) Ferrari 1:37.332
8. Rubens Barrichello (Bra) Honda 1:37.481
9. Jarno Trulli (Ita) Toyota 1:37.492
10. Scott Speed (U.S.) Toro Rosso - Cosworth 1:37.852