Mark Webber proved to be the one to beat in first practice for the Brazilian GP, edging Jenson Button at a sunny Interlagos circuit.
After the early runners had their say at the top of the timesheets, the session quickly became a battle of the Red Bulls and McLarens.
Sebastian Vettel led for a period of time before he was dropped as Button and Lewis Hamilton moved to the front. But, with 15 minutes remaining, it was Webber who emerged as the fastest driver, posting a 1:13.811.
And although his rivals attempted to take the P1 slot - and came extremely close to doing just that - it was Webber who claimed the first P1 of the Brazilian GP weekend.
Button had to settle for second, 0.014s off the pace while Hamilton was third, a further 0.136s behind.
Vettel dropped to fourht, finishing ahead of the Ferraris of Felipe Massa, who is determined to finish on the podium in his home grand prix, and Fernando Alonso.
However, the latter's session came to a premature halt when he experienced an engine problem four minutes before the end of practice. The Spaniard parked his car on the side of the track after asking his team if there was an issue with the engine.
There was and they told him to park it and switch off.
Michael Schumacher ended the morning's running in seventh place, 1.351s off the pace, ahead of Force India test driver Nico Hulkenberg and regular driver Paul di Resta.
Nico Rosberg completed the top ten in a session that saw very few incidents and those were just drivers testing the limits of the track.
01. Mark Webber Red Bull-Renault 1m13.811 26 laps
02. Jenson Button McLaren-Mercedes 1m13.825 + 0.014 25 laps
03. Lewis Hamilton McLaren-Mercedes 1m13.961 + 0.150 20 laps
04. Sebastian Vettel Red Bull-Renault 1m14.025 + 0.214 28 laps
05. Felipe Massa Ferrari 1m14.507 + 0.696 34 laps
06. Fernando Alonso Ferrari 1m14.541 + 0.730 26 laps
07. Michael Schumacher Mercedes 1m15.162 + 1.351 28 laps
08. Nico Hulkenberg Force India-Mercedes 1m15.178 + 1.367 28 laps
09. Paul di Resta Force India-Mercedes 1m15.241 + 1.430 31 laps
10. Nico Rosberg Mercedes 1m15.321 + 1.510 29 laps
11. Jaime Alguersuari Toro Rosso-Ferrari 1m15.468 + 1.657 29 laps
12. Romain Grosjean Renault 1m15.547 + 1.736 18 laps
13. Rubens Barrichello Williams-Cosworth 1m15.663 + 1.852 27 laps
14. Bruno Senna Renault 1m15.732 + 1.921 32 laps
15. Kamui Kobayashi Sauber-Ferrari 1m15.747 + 1.936 31 laps
16. Pastor Maldonado Williams-Cosworth 1m15.836 + 2.025 27 laps
17. Sergio Perez Sauber-Ferrari 1m15.979 + 2.168 35 laps
18. Jean-Eric Vergne Toro Rosso-Ferrari 1m16.052 + 2.241 33 laps
19. Heikki Kovalainen Lotus-Renault 1m16.514 + 2.703 33 laps
20. Luiz Razia Lotus-Renault 1m17.595 + 3.784 31 laps
21. Timo Glock Virgin-Cosworth 1m18.140 + 4.329 29 laps
22. Jerome D'Ambrosio Virgin-Cosworth 1m18.653 + 4.842 29 laps
23. Daniel Ricciardo HRT-Cosworth 1m18.952 + 5.141 33 laps
24. Jan Charouz HRT-Cosworth 1m19.577 + 5.766 37 laps
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