Vettel remains on top
Red Bull's Sebastian Vettel once again demonstrated his supremacy over his Formula One rivals as he posted the quickest time in second practice for Sunday's Chinese Grand Prix in Shanghai.
The reigning world champion was quickest in the morning's first session and maintained his stranglehold with another perfectly judged display, his time of one minute 37.688 seconds enough to eclipse second-placed man Lewis Hamilton by 0.166secs.
It was a low-key session for Vettel's team-mate Mark Webber, however, as the Australian appeared to concentrate on longer runs in the second RB7 to finish down in 10th place, 1.6secs down on the German.
Vettel is aiming to continue his perfect start to the season with another pole position and victory to add to those achieved in Australia and Malaysia. He leads the world championship on 50 points, 24 clear of nearest challenger Jenson Button.
Button was third in the afternoon practice session, just a tenth down on Hamilton as the McLaren team-mates again continued their bid to successfully integrate new floor and exhaust upgrades.
Mercedes, meanwhile, looked in better shape than they had in first practice. Nico Rosberg and Michael Schumacher topped the timesheets with 30 minutes remaining after switching to the softer tyre, but eventually settled for fourth and fifth respectively.
Felipe Massa was sixth for Ferrari, although his team-mate Fernando Alonso battled with hydraulic problems during the session and could only manage 14th from just 17 laps on track.
Adrian Sutil was seventh for Force India, but it was a bad session for his team-mate Paul di Resta, the Scotsman failing to get out for any of the 90-minute session due to a fuel pressure problem.
Renault's Nick Heidfeld was another to suffer, the German, who finished third at Sepang last Sunday, committing his second error of the day when he ran wide at turn two.
Heidfeld knocked loose the front wing of the R31 - as he did after a spin in the opening practice session - but was able to slowly recover to the pit lane entrance where his mechanics wheeled him back to the garage and patched him up. He recovered to finish in eighth, one place ahead of team-mate Vitaly Petrov.