Lewis Hamilton was just fourth fastest overall after the first day’s practice ahead of Sunday’s title-deciding Brazilian Grand Prix.
Hamilton’s title rival Felipe Massa was poised to delight his legion of fans at Interlagos by topping the timesheets at the end of both 90-minute sessions.
But former two-time world champion Fernando Alonso had other ideas and knocked Massa off top spot in the closing stages of the afternoon programme.
Massa was out in front in the opening session in his Ferrari, edging Hamilton into second place in his McLaren by 0.190 seconds with a lap time of one minute 12.305secs.
Although marginally slower in the afternoon, Massa was all set to again take the honours when Renault’s Alonso stole his thunder with a lap of 1:12.296secs.
Hamilton was a surprisingly lowly ninth in the second session – although setting the fourth fastest time overall – the kind of result he has to avoid in Sunday’s race to become the youngest champion in F1 history.
The Briton only has to finish in the top five to take the title, but struggled in stark contrast to a fortnight ago when he dominated in China en route to victory.
Conditions were hardly welcoming either as a grey, windy day was punctuated by the odd shower, upsetting any rhythm.
Heavy rain is forecast on Sunday, and as Massa has proven over the course of the season to date, he and his car have been unable to handle such conditions, and that could play into Hamilton’s hands.
On Friday, Hamilton finished over half a second down on former team-mate Alonso, with Toyota’s Jarno Trulli third and Kimi Raikkonen fourth in his Ferrari.
Toro Rosso’s Sebastian Vettel, Nelson Piquet for Renault and Nico Rosberg in his Williams were also ahead of Hamilton in sixth, seventh and eighth places.
Williams’ Kazuki Nakajima completed the top 10, followed by David Coulthard in his special-liveried Red Bull.
The Scot concludes his 15-season F1 career here in Sao Paulo, and to mark his retirement is backing the ’Wings for Life’ campaign, which supports research into spinal cord injuries.
The cream car had to be agreed to by all the teams before Red Bull could put the car on the track.
Jenson Button, meanwhile, was down in 18th in his Honda, over a second off Alonso’s pace.