Ryan Hunter-Reay was fastest on a wet track in the last practice before Sunday's Sao Paulo 300, which will likely be affected by rain for the third straight year.
Hunter-Reay set the pace in the morning warmup as drivers struggled to stay on track in wet conditions on the streets of South America's biggest city. Pole winner Will Power was third and Dario Franchitti, starting second, was 14th.
Rain has affected the Sao Paulo race every year since it joined the IndyCar calendar in 2010. It was put back to Monday last season, and the inaugural race was red flagged and finished at the two-hour limit after resuming.
Despite forecasts of rain all day Sunday, organizers expected that changes made to improve the track's drainage system would work and that the race would take place.
IndyCar officials and race promoters considered starting the race half an hour ahead of the scheduled time to avoid more rain in the afternoon. However, the race has been moved up only a few minutes.
The start time had already been moved up in advance because of the afternoon thunderstorms common in Sao Paulo this time of the year.
Ineffective drainage systems in the past made driving under heavy rain nearly impossible at the 2.5-mile, 11 turn temporary Anhembi circuit.
IndyCar also announced Sunday that Justin Wilson had his qualifying times voided because his car failed technical inspection, forcing him to start from the back of the 26-driver field. Wilson had qualified sixth. IndyCar said all cars ''must run either the cameras or dummy equipment'' supplied by organizers, which didn't happen on Wilson's car.
Four drivers received a 10-spot grid penalty for changing engines - Takuma Sato, Katherine Legge, Oriol Servia and Sebastien Bourdais.
