Sumo is facing a potential chasm at the top of the ancient sport for the first time in over 30 years after the only yokozuna, Terunofuji, announced his retirement on Friday. The Mongolian-born 33-year-old has been the only top-ranked sumo for more than three years, and only 73 wrestlers have reached his level in the history of the centuries-old sport.

But Terunofuji has struggled with injuries and withdrew from the ongoing New Year Grand Sumo Tournament in Tokyo on Thursday after forfeiting his bout. He told reporters on Friday that he was retiring to train young wrestlers after “a tough 14 years” in the ring.