The flight instructor and the student pilot were landing the tailwheel-equipped airplane at the destination airport. The flight instructor described that the student’s wheel landing was at the proper speed and aligned with the runway, but with a slight left drift. The student applied right rudder along with (inadvertent) right brake pressure. The flight instructor announced “I have the aircraft” but felt significant resistance on the flight controls. He repeated the call as the airplane approached the right side of the runway. As the airplane progressed toward the grass off the side of the runway, the flight instructor again verbalized that he was trying to take control of the airplane as the student pilot applied both brakes. The airplane then abruptly stopped and nosed over. The airplane’s vertical stabilizer was substantially damaged during the accident. The flight instructor reported that there were no preimpact mechanical malfunctions or failures of the airplane that would have precluded normal operation.