Mark Webber and Sebastian Vettel confirmed the suspicion that Red Bull Racing would again be a factor in the Chinese Grand Prix by breaking Mercedes' hold on the top of the timesheets in third practice.
The Australian ended the hour-long session by narrowly missing out on the fastest lap of the weekend, clocking 1min 35.323secs to knock McLaren's Lewis Hamilton out of the top spot he had held since Friday afternoon. Webber eventually wound up a couple of tenths clear of the field, with Hamilton doing enough to keep Vettel at bay.
Mercedes had dominated the two sessions on Friday, with each McLaren driver taking a turn in P1 and Mercedes duo Nico Rosberg and Michael Schumacher ensconced in second and fourth respectively. Come Saturday, McLaren maintained its top four status, with Button on the heels of Vettel, while Rosberg and Schumacher slipped back behind not just the Red Bulls, but also Fernando Alonso's Ferrari to end the day in sixth and seventh.
Behind Schumacher, Robert Kubica, Felipe Massa and Kamui Kobayashi rounded out the top ten, while Toro Rosso and Force India battled over the spots just behind.
Once again, the red flag made an appearance, this time after Renault rookie Vitaly Petrov speared off at the final corner, having run wide onto the artificial grass beyond the kerbs. The Russian subsequently missed the final quarter of an hour, and had to make do with 15th position.
That was still enough to keep him ahead of Sauber's Pedro de la Rosa and the two Williams drivers, with Rubens Barrichello 16th after a disappointing start to the team's F-duct experiment. A handful of exploratory runs early in the hour failed to provide the desired results, and the Brazilian was quickly switched back to a more conventional set-up for the rest of the weekend.
Timo Glock restored Virgin to the front of the new teams, as the British team mixed it with Lotus. Glock and team-mate Lucas di Grassi alternated with Heikki Kovalainen and Jarno Trulli, while HRT brought up the rear. There was further frustration for the latter's Karun Chandhok too, as the team was punished for breaking a gearbox seal without the permission of race officials. The five-place grid penalty should not make too much difference to the Indian's qualifying performance, however.