Nico Rosberg made it a hat-trick of free practice session fastest laps by posting the quickest effort in the final minutes of Saturday's hour-long outing.
Having swept both of Friday's longer sessions, the young German - who finished on the podium at the season-opener a little over twelve months ago - appeared content to allow his rivals a crack at fastest time in the final chance of track time before qualifying, but then vaulted himself into top spot with the quickest lap of the weekend so far.
There wasn't much in it as the chequered flag fell, with Rosberg's 1min 25.808secs effort just a scant 0.003secs clear of Jarno Trulli's best in the Toyota, and just over a tenth better than Jenson Button's Brawn as the top three all ducked below the 1min 26secs barrier.
Fourth-placed Felipe Massa narrowly failed to join them, but also beat Rosberg's benchmark time from Friday in the best of the Ferraris. He was easily the better of the two scarlet cars, however, as team-mate Kimi Raikkonen completed just five laps before being reduced to a crawl by a suspected hydraulics problem. The Finn had earlier been taken on a high-speed ride across the grass after the problem appeared to affect his power-steering.
The Finn wasn't the only one to explore beyond the limits of the track either, with nearly everyone finding grass or gravel at some point in the session. Sebastian Vettel was the other driver appearing to come off worst from an excursion, the hapless Red Bull driver suffering a wheel nut problem as a result and losing more time in the pits after a troubled Friday.
Massa's appearance in fourth, and Mark Webber's in seventh, will give those teams not running one of the more contentious diffuser designs some hope for qualifying and the race, but Williams, Toyota and Brawn again appeared to have the upper hand, filling the top three places as well as fifth and sixth - courtesy of Kazuki Nakajima and Rubens Barrichello - and eighth, with Timo Glock. Barrichello could have been better placed too, having lost potentially his best lap to a moment.
BMW Sauber twins Robert Kubica and Nick Heidfeld rounded out the top ten, both seven-tenths off the pace, while McLaren improved, but only to eleventh and twelfth as Heikki Kovalainen and Lewis Hamilton continued to struggle for pace. The world champion ended the hour 0.906secs off Rosberg's target.
Vettel, who had briefly topped the times before Trulli, Button and Barrichello made P1 a personal battle, wound up 13th, one spot ahead of Adrian Sutil who, at one point, appeared on course for another top ten berth, and a fraction quicker than Toro Rosso duo Sebastien Bourdais and Sebastien Buemi, who proved closely matched.
Renault, meanwhile, took its turn at the wrong end of the table, with Fernando Alonso and Nelson Piquet only kept off the bottom of the pile by Raikkonen's misfortune.