Lewis Hamilton set the pace in the first free practice for the Chinese Grand Prix - leading an official GP session for the first time in 2009, as the new aerodynamic package on the McLaren MP4-24 appeared to vault the world champion to the front of the pack.
Hamilton, who set his best time 60 minutes into practice, took full advantage of McLaren's new interim double-decker diffuser to outpace championship leader Jenson Button and Brawn GP team-mate Rubens Barrichello.
More encouraging still for McLaren was that Hamilton's team-mate Heikki Kovalainen was fourth fastest.
True to form in 2009, the first half an hour of the session was comprised mainly of rookie Sebastien Buemi data logging and mental marking in his Toro Rosso, but just before the 30-minute mark Toyota's Jarno Trulli became the first significant front-runner to post a fast time - 1:39.959.
The Italian immediately lowered that by 0.69 seconds before apparently suffering an electrical problem that blanked out his Toyota dashboard and rendered him pit-bound for around half an hour.
Meanwhile Hamilton, whose car featured several tweaks on top of the new diffuser, signaled his intentions with a 1:38.603 - though his best was quickly usurped when the Brawns of Jenson Button and Rubens Barrichello began to run seriously.
But just after the hour mark, Hamilton went quicker still, and his time of 1:37.334 proved unmatchable for the rest of the session. Encouragingly for the Woking team, Kovalainen stayed in touch with the leading trio for much of the session and ended it just 0.338s from the ultimate pace.
Mark Webber was fifth fastest for Red Bull ahead of Trulli, who recovered to sixth, and this year's free practice star Nico Rosberg, who worked down to a quiet seventh for Williams.
Toyota's Timo Glock ran off track a couple of times during the session en route to eighth place, ahead of Fernando Alonso's Renault. Sebastien Bourdais' tenth place, paired with Buemi's 13th, also indicated that Toro Rosso is making progress with its STR4.
Not so happy was Ferrari. Kimi Raikkonen could only manage 11th, while team-mate Felipe Massa complained of severe graining on his way to 14th. Both ran off-track at Turn 14 early on and the Brazilian would later spin at the same corner.
Others to have small moments during a session devoid of any major stoppages included Williams's Kazuki Nakajima, Renault's Nelson Piquet and BMW's Nick Heidfeld.
Pos Driver Team Time Laps
1. Hamilton McLaren-Mercedes (B) 1:37.334 + 22
2. Button Brawn GP-Mercedes (B) 1:37.450 + 0.116 18
3. Barrichello Brawn GP-Mercedes (B) 1:37.566 + 0.232 19
4. Kovalainen McLaren-Mercedes (B) 1:37.672 + 0.338 23
5. Webber Red Bull-Renault (B) 1:37.752 + 0.418 20
6. Trulli Toyota (B) 1:37.764 + 0.430 19
7. Rosberg Williams-Toyota (B) 1:37.860 + 0.526 24
8. Glock Toyota (B) 1:37.894 + 0.560 21
9. Alonso Renault (B) 1:38.089 + 0.755 19
10. Bourdais Toro Rosso-Ferrari (B) 1:38.195 + 0.861 24
11. Raikkonen Ferrari (B) 1:38.223 + 0.889 23
12. Vettel Red Bull-Renault (B) 1:38.274 + 0.940 20
13. Buemi Toro Rosso-Ferrari (B) 1:38.307 + 0.973 26
14. Sutil Force India-Mercedes (B) 1:38.319 + 0.985 18
15. Massa Ferrari (B) 1:38.418 + 1.084 20
16. Heidfeld BMW Sauber (B) 1:38.456 + 1.122 21
17. Fisichella Force India-Mercedes (B) 1:38.460 + 1.126 19
18. Kubica BMW Sauber (B) 1:38.463 + 1.129 18
19. Nakajima Williams-Toyota (B) 1:38.730 + 1.396 25
20. Piquet Renault (B) 1:38.825 + 1.491 20
All timing unofficial