Jenson Button lapped Shanghai half a second under last year's Chinese Grand Prix pole position time as he established himself and the Brawn GP team at the top of the times for this year's event.
The Briton and teammate Rubens Barrichello dominated for most of the second 90-minute session on Friday as teams began experimenting with super-soft tire – with varying success.
But as has become the norm for Fridays, Nico Rosberg sneaked a fast lap in late in the session to split white machines to go second.
While the softer rubber, the selection of which has come in for criticism by some of the drivers, clearly proved to be the faster option. But graining and degradation were major factors, with chunks of rubber bouncing back into drivers' helmets in certain corners.
Until half-distance, it was the Red Bulls of Sebastian Vettel and Mark Webber that held sway, having usurped early pace-setters. But that all changed once the Brawn's emerged from the pits.
It wasn't championship leader Button that set the pace though, rather Barrichello, whose sequence of laps culminating in a 1:35.881 put him top of the pile.
It looked as if the Brazilian might finally get the better of his team-mate this year, but Button was having none of it. On another set of green-rimmed softs, he went about deposing Barrichello. And after his first lap was aborted when he was held up by Kimi Raikkonen recovering on to the track in front of him, Button posted a 1:35.679.
That ended any debate at the top. That is except for Rosberg, who might have been even faster than second had he not locked up at the end of the straight on another quick lap.
Webber was fourth fastest behind Barrichello. The Australian posted a late flier to push Vettel down to fifth while Toyota's Jarno Trulli was sixth.
Kazuki Nakajima improved to seventh late-on ahead of Timo Glock in the second Toyota. Heikki Kovalainen did a solid job in the slightly less evolved of the two McLaren MP4-24s to go ninth ahead of Sebastien Bourdais who once again cracked the top ten.
Adrian Sutil was 11th fastest despite several spins, half-spins and off-track moments for both him and his Force India teammate Giancarlo Fisichella.
The grandee teams all had a difficult session, as with the exception of Kovalainen, all of McLaren, Ferrari, BMW and Renault's drivers floundered outside the top 10.
Pos Driver Team Time Laps
1. Button Brawn-Mercedes (B) 1:35.679 35
2. Rosberg Williams-Toyota (B) 1:35.704 + 0.025 36
3. Barrichello Brawn-Mercedes (B) 1:35.881 + 0.202 35
4. Webber Red Bull-Renault (B) 1:36.105 + 0.426 32
5. Vettel Red Bull-Renault (B) 1:36.167 + 0.488 22
6. Trulli Toyota (B) 1:36.217 + 0.538 42
7. Nakajima Williams-Toyota (B) 1:36.377 + 0.698 32
8. Glock Toyota (B) 1:36.548 + 0.869 40
9. Kovalainen McLaren-Mercedes (B) 1:36.674 + 0.995 34
10. Bourdais Toro Rosso-Ferrari (B) 1:36.800 + 1.121 34
11. Sutil Force India-Mercedes (B) 1:36.829 + 1.150 30
12. Massa Ferrari (B) 1:36.847 + 1.168 34
13. Hamilton McLaren-Mercedes (B) 1:36.941 + 1.262 28
14. Raikkonen Ferrari (B) 1:37.054 + 1.375 33
15. Buemi Toro Rosso-Ferrari (B) 1:37.219 + 1.540 34
16. Piquet Renault (B) 1:37.273 + 1.594 36
17. Kubica BMW-Sauber (B) 1:37.491 + 1.812 34
18. Heidfeld BMW-Sauber (B) 1:37.544 + 1.865 28
19. Alonso Renault (B) 1:37.638 + 1.959 28
20. Fisichella Force India-Mercedes (B) 1:37.750 + 2.071 31
All Timing Unofficial