Jenson Button reasserted his and Brawn GP’s supremacy by topping the second practice session in Shanghai on Friday afternoon.
But it was far from a cakewalk for the in-form British driver, as Nico Rosberg again showed impressive practice pace for Williams and finished just 0.025s adrift, relegating Rubens Barrichello in the other Brawn to third place.
Red Bull Racing’s Mark Webber and Sebastian Vettel were next up ahead of Toyota’s Jarno Trulli, the second Williams of Kazuki Nakajima and the second Toyota of Timo Glock.
McLaren was unable to reproduce the performance that saw Lewis Hamilton top the first practice charts, with Heikki Kovalainen its best-placed driver in ninth and Hamilton down in 13th between the struggling Ferraris.
Sebastien Bourdais seems to have found a much better groove in Shanghai than at the first two races and repeated his strong morning showing to take 10th for Toro Rosso.
After the STR and then the Williams drivers traded fastest time in the early stages, Trulli laid down the first benchmark for a super-soft tyre run with a 1m36.684s lap 22 minutes into the session.
The Italian shaved a further 0.3s off that to stave off a challenge from Toyota team-mate Glock, but within a few minutes they were both demoted by the Red Bull duo as Webber clocked a 1m36.179s and then Vettel instantly pipped him with a 1m36.167s.
This quartet held station at the top of the timing charts for nearly half an hour, at which point Brawn GP turned up the wick.
Barrichello produced the first sub-1m36s lap with a 1m35.995s before team-mate Button upped the ante to 1m35.679s, which would remain unbeaten.
Rosberg came close during the closing stages, and was ahead of Button after the first two sectors of his final flier only to lose some 0.3s in the last part of the lap – perhaps indicating that the Brawn is kinder to the super-soft rubber than the Williams.
A previous bid had been scuppered when Rosberg locked the rear axle under braking for the first-gear turn 14 hairpin, but if the German can carry his speed into qualifying he should be a major factor again on Sunday.
The well-matched Red Bull pair swapped places in the final shake-out so Webber won the intra-team bragging rights, while Nakajima looked much happier than in the morning even if he still trailed Rosberg by nearly 0.7s.
The McLarens were quick on hard tyres during the early runs, but faded after switching to the soft rubber.
Hamilton again had the revised diffuser on his car, which seems to produce considerably more rear downforce, while Kovalainen’s older-spec MP4-24 was now also equipped with the new front wing.
The Ferraris continued to look a handful around the 3.4-mile circuit as well as slow on the stopwatch, and Felipe Massa and Kimi Raikkonen had a number of ragged moments en route to the 12th and 14th fastest times respectively.
The BMWs had another low-key session and wound up 17th (Robert Kubica) and 18th (Nick Heidfeld) ahead of Renault’s Fernando Alonso.
The Spaniard’s team-mate Nelson Piquet managed 16th, despite a heart-stopping moment in the sixth-gear turn seven.
That same high-speed corner caught out Giancarlo Fisichella, who lost the back end of his Force India midway through and had a dramatic – but harmless – spin.
Team-mate Adrian Sutil had a similar off in the tricky tightening-up ‘snail’ of turns one and two but set an excellent 11th best time nonetheless.
Chinese Grand Prix free practice session two
1. BUTTON Brawn 1m35.679s
2. ROSBERG Williams 1m35.704s
3. BARRICHELLO Brawn 1m35.881s
4. WEBBER Red Bull 1m36.105s
5. VETTEL Red Bull 1m36.167s
6. TRULLI Toyota 1m36.217s
7. NAKAJIMA Williams 1m36.377s
8. GLOCK Toyota 1m36.548s
9. KOVALAINEN McLaren 1m36.674s
10. BOURDAIS Toro Rosso 1m36.800s
11. SUTIL Force India 1m36.829s
12. MASSA Ferrari 1m36.847s
13. HAMILTON McLaren 1m36.941s
14. RAIKKONEN Ferrari 1m37.054s
15. BUEMI Toro Rosso 1m37.219s
16. PIQUET Renault 1m37.273s
17. KUBICA BMW 1m37.491s
18. HEIDFELD BMW 1m37.544s
19. ALONSO Renault 1m37.638s
20. FISICHELLA Force India 1m37.750s