Renault's Fernando Alonso set the pace in Brazilian Grand Prix practice on Friday while home hero Felipe Massa lapped comfortably quicker than title favourite Lewis Hamilton.
Alonso, who took his two Formula One titles at Interlagos in 2005 and 2006 but is out of the reckoning this time, set a best time of one minute 12.296 seconds on a damp and blustery afternoon.
Ferrari's Massa was fastest in the morning in 1:12.305 and led the timesheets after lunch until Alonso put in a late quick lap.
The Brazilian, seven points behind McLaren's Hamilton, is embarking on the final stage of what some see as a Mission Impossible to prevent the 23-year-old becoming Formula One's youngest champion on Sunday.
"It might only be Friday, but it's important to get off to a good start on such an important weekend," said Massa. "We found a good set-up for the car, which seemed to be well balanced in both sessions.
"Racing at home, with the crowd on your side, is a great motivation for me."
Hamilton, who blew his title chance in the Brazilian season-ender last year, was second in the morning and ninth in the afternoon after repeatedly locking his brakes on the wet track.
"Our car was blindingly quick this morning despite the cold weather, which made the track feel quite slippery," said Hamilton.
"This afternoon we focussed on our race pace but we were interrupted by the threat of rain and the changeable wind direction."
Ferrari's outgoing champion Kimi Raikkonen, the Finn who made up a seven-point deficit to beat Hamilton by a single point in 2007, was third and fourth respectively.
Hamilton needs only finish fifth on Sunday to be champion, even if Massa wins his home race as expected, and will be unlikely to push too hard in what will be the second race for his Mercedes engine.
Both the Ferraris have new engines for Brazil, a boost for their bid to retain the constructors' championship. They lead McLaren by 11 points with a maximum 18 to be won.
"We don't have to win (the race) so that is a pressure off our shoulders," Hamilton said after his arrival at the circuit on Thursday.
"We have not come here to finish further down the order but we obviously know it is not do or die."
Poland's Robert Kubica, fighting to end the season in third place for BMW-Sauber, was fourth fastest in the morning with McLaren's Heikki Kovalainen fifth.
Toyota's Italian Jarno Trulli was third in the afternoon.
(Editing by Tony Jimenez and Ken Ferris)