Just as he did in Korea two weeks ago, Robert Kubica showed that Renault could be a fly in the ointment for the title contenders by posting the fastest time in a damp final practice session at Interlagos.
The Pole moved to the head of the timesheets on a drying track, after the hour-long session began in steady rain. His best lap, a 1min 19.191secs effort, was good enough to ease Friday pacesetter Sebastian Vettel out of top spot, the German having previously recorded a 1min 19.500secs lap for Red Bull.
The top six drivers all broke into the 1min 19s, with three others within a second of Kubica's pace, but the conditions conspired to string the field out, with the likes of Mark Webber, second on Friday, 1.146secs adrift in eleventh after deciding to sit out much of the poorest conditions in order to save his tyres and engine. McLaren's Jenson Button was only two places better off, while renowned wet weather expert Michael Schumacher was twelfth.
Kubica and Vettel were chased hard by Lewis Hamilton, who wound up just 0.036secs shy of the German after swapping the higher downforce rear wing for a lighter one, while Felipe Massa and Fernando Alonso ensured a better showing for Ferrari, which ended the morning with two cars in the top five. Vitaly Petrov, in the second Renault, was the other driver in the 1min 19s after surviving the conditions with his car intact, while Sebastien Buemi (Toro Rosso), Nico Rosberg (Mercedes) and Williams' Rubens Barrichello completed the top ten.
With Sauber and Force India helping to prop up the established teams, one-and-a-half seconds split Nick Heidfeld from leading newcomer Lotus, which again had Jarno Trulli to thank for 19th spot. The Italian was just over a tenth quicker than Virgin's Timo Glock, with Heikki Kovalainen and Lucas di Grassi in line astern ahead of Bruno and Senna, who edged 'new' HRT team-mate Christian Klien for 23rd spot.
More rain is forecast ahead of qualifying, suggesting that pole position could come down to who is running last on track when the chequered flag falls.