Felipe Massa proved Ferrari's position as favourites for the British Grand Prix when he set the fastest time on the first day of testing at Silverstone on Tuesday.
The Brazilian edged out McLaren's Heikki Kovalainen by almost three tenths of a second as his team began their three-day preparations for next weekend's race.
Ferrari will, however, have been left concerned by a mechanical failure that resulted in Massa being left stranded on track 30 minutes from the end of the session to bring out a red flag.
Robert Kubica was a further half a second adrift of Kovalainen, as his BMW Sauber team bid to bounce back from their disappointing performance in Magny-Cours, where they failed to show the form that had helped them to their maiden in Canada earlier this month.
The team tried out a new front wing that they hope will lift them back into contention in the fight against Ferrari and McLaren.
Toyota delivered evidence of their improving form as test driver Kamui Kobayashi was fourth fastest on his first visit to the track in an F1 car, although he also brought out a red flag when his engine died at Becketts.
Nico Rosberg was fifth fastest, ahead of Mark Webber in the Red Bull Racing. Seventh fastest Nelson Piquet brought out a red flag when he stopped just after 3pm on the main straight.
Vitantonio Liuzzi tried some aerodynamic and mechanical developments on the Force India, but the team did not run the full 'shark fin' engine cover that is expected to be evaluated this week.
The most disappointed man of the day was Sebastian Vettel, who only managed to complete 10 laps after stopping with a fuel system problem in his Scuderia Toro Rosso STR3. The team expect the German to be back out in action tomorrow.
Pos Driver Team Time Laps 1. Massa Ferrari (B) 1:20.188 71 2. Kovalainen McLaren-Mercedes (B) 1:20.477 90 3. Kubica BMW Sauber (B) 1:20.995 82 4. Kobayashi Toyota (B) 1:21.335 82 5. Rosberg Williams-Toyota (B) 1:21.410 88 6. Webber Red Bull-Renault (B) 1:21.656 94 7. Piquet Renault (B) 1:21.797 68 8. Button Honda (B) 1:22.081 90 9. Liuzzi Force India (B) 1:22.250 108 10. Vettel Toro Rosso-Ferrari (B) 1:23.853 10 All Timing Unofficial