(CNN) -- Fernando Alonso topped the times for Renault in Friday's second free practice session ahead of Sunday's potentially decisive Brazilian Grand Prix at Interlagos.
Fernando Alonso proved quickest in practice for Sunday's Brazilian Grand Prix at Interlagos.
The 28-year-old Ferrari-bound Spaniard clocked his best lap of 1:12.314 in the final seconds of a closely-contested session run in cool and damp conditions with showers disrupting the action.
Alonso's quickest lap lifted him clear of second-placed Sebastien Buemi of Toro Rosso with local hero Rubens Barrichello of Brawn GP third -- as he aims for the victory that will keep his slim world title hopes alive.
Australian Mark Webber was fourth fastest for Red Bull ahead of Barrichello's team-mate and championship leader Jenson Button.
The 29-year-old Englishman needs only to finish on the podium in Sunday's 71-lap contest to secure the world title.
Italian Jarno Trulli took sixth place for Toyota ahead of the third championship contender, Sebastian Vettel, in the second Red Bull.
German Nico Rosberg finished eighth for Williams ahead of Force India's Adrian Sutil and outgoing champion Lewis Hamilton, who was 10th for McLaren Mercedes.
Ferrari endured a bad day with Kimi Raikkonen down in 18th place, one behind compatriot Heikki Kovalainen of McLaren, and Giancarlo Fisichella 20th.
Remarkably only seven-tenths of a second separated Alonso, at the front of the field, from 19th-placed Jaime Alguersuari of Toro Rosso.
In the cool conditions, there was little noteworthy action until the closing stages when Alonso shot from nowhere to top the times.
Earlier, Webber was quickest in the morning, with the 33-year-old Australian emerging on top after a disjointed session.
Webber produced a best lap of one minute and 12.463 seconds around the demanding circuit to finish narrowly ahead of Barrichello.
Vettel was third quickest, but Button made his now almost-customary slow start to the action by finishing in seventh place.