Fernando Alonso and Sebastien Buemi surprised the title contenders by posting the fastest practice times of the day ahead of Sunday's Brazilian Grand Prix.

Ferrari-bound Alonso ousted the surprise name of Toro Rosso's Buemi from top spot in the final moments in his Enstone-built Renault with a lap of one minute and 12.314 seconds, pipping the Swiss by just 0.043 seconds.

Rubens Barrichello was the best of the championship contenders with the third best time in his Brackley-built Brawn GP, two places ahead of team-mate and title leader Jenson Button in fifth, with Sebastian Vettel in the Red Bull seventh.

The scene is clearly now set for an enthralling qualifying session around the famed Interlagos circuit on Saturday, with all three of the main protagonists in good form.

Button, though, did complain of understeer, oversteer and a failure to get heat into his tyres on occasion, the latter unsurprising due to the cooler than usual conditions in Sao Paulo at this time of year.

However, the 29-year-old Briton can be happy with his day's work ahead of the most important race of his career, knowing all he requires are just six points to be crowned champion.

Mark Webber, who was quickest in the first practice session, had to settle for fourth in his Red Bull with a time a fraction slower than his best in the opening 90 minutes.

Separating Button and Vettel was Toyota's Jarno Trulli, with Nico Rosberg in his Grove-built Williams and Silverstone-based Force India's Adrian Sutil remarkably eighth and ninth again as they were first time out.

World champion Lewis Hamilton was 10th in his McLaren, followed by Romain Grosjean for Renault and BMW Sauber's Robert Kubica, with the top 12 separated by just half a second.

In a poor session for Ferrari, Kimi Raikkonen was a lowly 18th, while there was further embarrassment for Giancarlo Fisichella who stalled to finish at the foot of the timesheets, just under a second down on Alonso.