The pilot reported the approach and landing were normal, and he used right rudder to compensate for a left crosswind. During the landing roll the pilot's left foot slid off the rudder pedal and the airplane began to veer to the right. When he moved his foot back on the rudder pedal, he inadvertently applied the left brake. The pilot added right rudder to compensate; however, the airplane traveled off the left side of the runway. The pilot added power in an attempt to avoid a ditch alongside the runway, but the airplane contacted the ditch and nosed over resulting in substantial damage to the fuselage and wings. The pilot reported that there were no mechanical failures/malfunctions of the airplane.