Mercedes' Nico Rosberg was fastest in the second practice for Formula One's season-ending Brazilian Grand Prix on Friday, edging Sebastian Vettel and his Red Bull teammate Mark Webber on a wet Interlagos track.
Vettel, who has already clinched his fourth straight F1 title, enters the finale with a chance to equal Michael Schumacher's 13 victories in a year and match the record of nine consecutive wins by Alberto Ascari in the 1952 and 1953 seasons.
Rosberg timed 1 minute, 27.306 seconds in the afternoon session at the 4.3-kilometer (2.6-mile) track in Sao Paulo, .225 ahead of Vettel and .286 in front of Webber, who is competing in his last F1 race at the Brazilian GP.
The Australian driver, who will join Porsche's endurance program, has won two of the last four races at Interlagos.
Rosberg had been fastest in the first practice session with a lap of 1:24.781, when track conditions were better. Mercedes teammate Lewis Hamilton was second and Vettel was third in the morning despite briefly running off the track near the end of the session. Hamilton spun and recovered in both sessions.
It rained heavily in the afternoon and drivers couldn't switch to intermediary tires until the final minutes.
Vettel was the only driver to test the prototype dry weather tires that will be used by teams in 2014. Vettel ran a lap with them in the first session despite the damp track, but it was enough to give engineers at least some information that might be useful for next season.
Teams and drivers know little about what to expect next year because the series will go through a major change in engine rules, switching from the current 2.4-litre V8 units to a 1.6-litre V6 turbocharged engine, a move that will demand significant alterations in the design of cars.
The Brazilian GP marks the last race before several driver changes at some of F1's top teams. World champion Kimi Raikkonen of Finland leaves Lotus for Ferrari, where Felipe Massa lost his ride before joining Williams. The Brazilian replaces Pastor Maldonado of Venezuela, who could be up for the Raikkonen seat at Lotus.
McLaren will replace Mexican Sergio Perez with rookie Kevin Magnussen of Denmark, and Australian Daniel Ricciardo, from Red Bull's sister team Toro Rosso, will replace Webber.