Alonso fastest at drying Albert Park
Even for F1's revised format for opening practice, however, it was an atypical session, with the circuit only drying up enough for dry tires and competitive laps right at the very end of the 90 minute sitting.
Even so, the Spaniard's McLaren was a whopping 1.5 seconds clear of second best man Felipe Massa, in his red Ferrari, but Alonso lapped the Melbourne layout 23 times compared to the Brazilian's meagre seven.
Massa's teammate Kimi Raikkonen, in contrast, was a lowly nineteenth, and the 2006-style excuse of saving mileage is not applicable this year as teams are now allowed to change their engines ahead of Saturday practice without penalty.
For most of the hour and a half, cars flicked up spray after heavy rain left early risers scrambling for cover just south of Melbourne city's central business district.
BMW's test driver Sebastian Vettel was third quickest at the end of the morning, ahead of GP2 champion Lewis Hamilton, who this year is Alonso's rookie teammate.
A worrying omen for Toyota was the pace of Ralf Schumacher and Jarno Trulli; albeit split by Scott Speed's Toro Rosso, the highly paid pair brought up the very rear of the times..
Friday AM Times
Pos Driver Team Time Laps
1. Alonso McLaren-Mercedes 1:29.214 23
2. Massa Ferrari 1:30.707 + 1.493 7
3. Vettel BMW Sauber 1:30.857 + 1.643 22
4. Hamilton McLaren-Mercedes 1:30.878 + 1.664 14
5. Button Honda 1:31.162 + 1.948 15
6. Nakajima Williams-Toyota 1:31.401 + 2.187 21
7. Coulthard Red Bull-Renault 1:31.528 + 2.314 9
8. Kovalainen Renault 1:31.571 + 2.357 20
9. Webber Red Bull-Renault 1:31.661 + 2.447 16
10. Barrichello Honda 1:31.737 + 2.523 12
11. Sato Super Aguri-Honda 1:31.782 + 2.568 7
12. Fisichella Renault 1:32.011 + 2.797 14
13. Wurz Williams-Toyota 1:32.194 + 2.980 18
14. Albers Spyker-Ferrari 1:34.043 + 4.829 26
15. Liuzzi Toro Rosso-Ferrari 1:34.627 + 5.413 8
16. Sutil Spyker-Ferrari 1:35.055 + 5.841 10
17. Heidfeld BMW Sauber 1:37.249 + 8.035 12
18. Davidson Super Aguri-Honda 1:39.221 + 10.007 6
19. Raikkonen Ferrari 1:39.242 + 10.028 7
20. R.Schumacher Toyota 1:39.550 + 10.336 9
21. Speed Toro Rosso-Ferrari 1:41.763 + 12.549 9
22. Trulli Toyota 1:44.130 + 14.916 11