Japanese sumo officials are investigating allegations that nine-time grand champion Harumafuji assaulted a lower-ranked wrestler, causing serious head injuries.
Japanese media reported that Harumafuji hit his fellow Mongolian wrestler Takanoiwa in the head with a beer bottle at a party last month, fracturing his skull base and causing other injuries.
Harumafuji, who holds sumo's highest ranking of yokozuna, appeared on Japanese television to acknowledge his role in the incident and apologise for his actions.
The Japan Sumo Association, which imposes strict rules on wrestlers, said 33-year-old Harumafuji will sit out the 15-day Fukuoka tournament that started Sunday while investigation takes place.
The incident is the latest scandal to rock the sport of sumo in recent years following investigations into hazing and match-fixing.
