Ferrari test driver Luca Badoer set the fastest time on the first day of a three-day test session at Barcelona's Circuit de Catalunya.
The Italian hit the top of the timesheets early in the morning and, with raining hitting the track in the afternoon, he retained the position throughout the day.
Badoer spent the day working on aerodynamic developments and ended the day with a best time of one minute 22.412 seconds.
He was therefore two-tenths of a second quicker than Canadian Grand Prix winner Robert Kubica.
The BMW Sauber driver clocked a 1:22.682s despite spending part of the morning stuck in his garage while the team fixed a mechanical problem.
Third and fourth places went to Red Bull's drivers, with David Coulthard leading Sebastien Buemi.
Gary Paffett was fifth quickest for McLaren Mercedes, finishing ahead of Anthony Davidson, who was making a return to testing for Honda.
The Briton had not driven an F1 car on a circuit since the Spanish Grand Prix, the last race contested by the Super Aguri outfit.
Williams tester Nico Hulkenberg finished the day seventh quickest ahead of Renault test driver Romain Grosjean - the GP2 driver making his debut.
Toyota's Kamui Kobayashi finished the day slowest of all in ninth place.
Barcelona testing, day one:
1. Luca Badoer Ferrari 1:22.412 82 laps
2. Robert Kubica BMW Sauber 1:22.682 69 laps
3. David Coulthard Red Bull 1:22.724 21 laps
4. Sebastien Buemi Red Bull 1:22.764 79 laps
5. Gary Paffett McLaren 1:22.938 36 laps
6. Anthony Davidson Honda 1:23.208 81 laps
7. Nico Hulkenberg Williams 1:23.619 112 laps
8. Romain Grosjean Renault 1:23.899 60 laps
9. Kamui Kobayashi Toyota 1:24.442 82 laps

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