Yoshinori Sasaki (Japanese: 佐々木 嘉則, Sasaki Yoshinori, born 23 July 1974) is a Japanese professional wrestler and retired sumo wrestler and mixed martial artist, currently working for Pro Wrestling Freedoms under the ring name Mammoth Sasaki (マンモス佐々木, Manmosu Sasaki), where he is a former King of Freedom Tag Team Champion, becoming the longest reigning champion during his second reign with the title. He is best known for his time with Frontier Martial-Arts Wrestling (FMW), where he competed between 1997 until the promotion's closure in 2002.