Takuma Sato made a sensational return to Formula One action when he topped the times in testing at the Barcelona circuit in Spain.
All grand prix teams, except Toyota, returned to work just two weeks after the end of the 2008 season to begin preparing for the challenges of next year's campaign, when several new regulations will be introduced.
A total of 17 drivers took to the track today, in a field full of test drivers and F1 hopefuls, including Sato himself, who tested for Toro Rosso for the second time this year.
The Japanese, aiming to secure a race seat at the Italian squad, posted a best time of 1:20.763 in the 2008-spec car, fitted with Bridgestone's slick tyres.
Toro Rosso dominated the opening day of testing thanks to Red Bull's test driver Sebastien Buemi finished in second behind Sato in a similar car.
Honda's Alex Wurz was third quickest in a revised RA108, as the team evaluated new aero components for next season as well as the new slicks.
McLaren's testers Pedro de la Rosa and Gary Paffett completed the top five as the British squad began testing with their KERS system onboard. Only de la Rosa carried the system onboard.
The BMW Sauber team caught the most eyes today thanks to the introduction of a 2009-spec aerodynamic package, which made their car very distinguishable. Both Robert Kubica and Christian Klien were at the wheel of the hybrid car, with the Austrian the other driver on track who tested with KERS.
Ferrari also had two cars on track, both modified to simulate 2009 downforce levels. Luca Badoer's car also simulated carrying the KERS system.
Five-time world rally champion Sebastien Loeb completed his second outing in Formula One machinery, testing for the Red Bull team. The Frenchman, who had previously driven a Renault F1 car, was an impressive eighth quickest, less than 1.5 seconds off the pace.
GP2 championship runner-up Bruno Senna finally made his Formula One debut, joining the Honda Racing team for their first day of work. The Brazilian shared the car with compatriot Lucas di Grassi and posted the 15th quickest time of the session, more than a second ahead of the Renault test driver.
The Brazilian duo were split by Giedo van der Garde, who tested for Renault as a reward for winning the World Series title. The Dutchman managed just 27 laps after crashing out at around 3:30pm.
The other two red flags of the day were caused by Kubica stopping on track in the morning and by Williams's Nico Hulkenberg.
Pos Driver Team Time Laps 1. Sato Toro Rosso-Ferrari (B) 1:20.763 121 2. Buemi Toro Rosso-Ferrari (B) 1:21.071 117 3. Wurz Honda (B) 1:21.198 77 4. de la Rosa McLaren-Mercedes (B) 1:21.417 65 5. Badoer Ferrari (B) 1:22.038 93 6. Paffett McLaren-Mercedes (B) 1:22.235 47 7. Kubica BMW-Sauber (B) 1:22.341 56 8. Loeb Red Bull-Renault (B) 1:22.503 82 9. Piquet Renault (B) 1:22.560 80 10. Klien BMW-Sauber (B) 1:22.883 53 11. Hulkenberg Williams-Toyota (B) 1:23.467 116 12. Liuzzi Force India-Ferrari (B) 1:23.794 86 13. Sutil Force India-Ferrari (B) 1:23.832 88 14. Gene Ferrari (B) 1:24.117 32 15. Senna Honda (B) 1:24.343 39 16. van der Garde Renault (B) 1:24.908 27 17. di Grassi Honda (B) 1:25.512 48 All Timing Unofficial