 Complete the following phrase:  During the 1993 season, Prost and Senna continued their on-track rivalry. Prost was escorted by police to the Interlagos circuit for the 1993 Brazilian Grand Prix due to the hostility of Brazilians towards him. The two continued their on-track battles at Silverstone where Senna aggressively defended his position against Prost. At Prosts last Grand Prix, the 