Button opened the first official session with the fastest time:

Pos Driver Team Time Laps
1. Jenson Button McLaren-Mercedes 1m27.560s 11
2. Lewis Hamilton McLaren-Mercedes 1m27.805s + 0.245 14
3. Michael Schumacher Mercedes 1m28.235s + 0.675 17
4. Fernando Alonso Ferrari 1m28.360s + 0.800 21
5. Mark Webber Red Bull-Renault 1m28.467s + 0.907 21
6. Nico Rosberg Mercedes 1m28.683s + 1.123 22
7. Daniel Ricciardo Toro Rosso-Ferrari 1m28.908s + 1.348 23
8. Pastor Maldonado Williams-Renault 1m29.415s + 1.855 16
9. Kimi Raikkonen Lotus-Renault 1m29.565s + 2.005 8
10. Kamui Kobayashi Sauber-Ferrari 1m29.722s + 2.162 26
11. Sebastian Vettel Red Bull-Renault 1m29.790s + 2.230 21
12. Nico Hulkenberg Force India-Mercedes 1m29.865s + 2.305 17
13. Paul di Resta Force India-Mercedes 1m29.881s + 2.321 18
14. Bruno Senna Williams-Renault 1m29.953s + 2.393 21
15. Sergio Perez Sauber-Ferrari 1m30.124s + 2.564 22
16. Romain Grosjean Lotus-Renault 1m30.515s + 2.955 16
17. Heikki Kovalainen Caterham-Renault 1m30.586s + 3.026 16
18. Felipe Massa Ferrari 1m30.743s + 3.183 11
19. Jean-Eric Vergne Toro Rosso-Ferrari 1m31.178s + 3.618 17
20. Vitaly Petrov Caterham-Renault 1m31.983s + 4.423 8
21. Timo Glock Marussia-Cosworth 1m34.730s + 7.170 8
22. Charles Pic Marussia-Cosworth 1m40.256s + 12.696 11
23. Narain Karthikeyan HRT-Cosworth no time 3
24. Pedro de la Rosa HRT-Cosworth no time 0

Jenson Button fastest for McLaren in opening Australian Grand Prix practice - F1 news - AUTOSPORT.com