The only man who Sensei Ping could not defeat, El Sapo Dorado was the former leader of the Mexican Luchadores. After traveling the world searching for a warrior who could defeat him, he challenged Sensei Ping to a series of duels over twenty-five days, including:
- Hand-to-hand combat
- Swordfighting
- Airborne combat in fighter planes
- Rock 'Em Sock 'Em Robots
On the twenty-sixth day of battle, while playing Rock 'Em Sock 'Em Robots, El Sapo Dorado suffered a heart attack and died. Sensei Ping took and wore his mask to honor him in death, the only man Sensei Ping could not defeat.
However, El Maestro De Ceremonies and the Mexican Luchadores believed that Sensei Ping had murdered El Sapo Dorado in cold blood, and held a blood feud against him, intending to kill him. They had their chance when they captured Sensei Ping with La Cage De Lumiere and took him to the Dread Pyramid of Itzilichlitlichlitzl, but he escaped with help from Wendy Watson and his apprentice, and wiped out the Luchadores.