Grand champion Musashimaru has decided to retire from sumo after suffering his fourth loss in the Kyushu Grand Sumo Tournament on Saturday, news reports said.
Revitalized ozeki Tochiazuma, meanwhile, remained unbeaten and tied for the lead.
Fighting in the penultimate bout at Fukuoka Kokusai Center, No. 2 maegashira Tosanoumi got a hold of Musashimaru's arm and pulled the struggling yokozuna to the edge, where his weight carried him out over the straw ridge.
Musashimaru, who has missed all or parts of the last six tournaments due to an injured left wrist, dropped to 3-4.
National broadcaster NHK, citing Musashimaru's stablemaster, Musashigawa, reported after Saturday's bouts that Musashimaru had decided to retire from sumo.
In other major bouts, Mongolian grand champion Asashoryu, who won the Autumn tournament and is gunning for his fifth title, took on compatriot Kyokutenho and improved to 6-1 when he lifted the struggling sekiwake out to his sixth loss.
Tochiazuma maintained his perfect record when he got a hold of Aminishiki's neck with his right hand and then forced the struggling third-ranked maegashira out over the edge for win. No. 7. Aminishiki fell to 1-6. Ozeki Chiyotaikai bounced back from Friday's loss to Tamanoshima when he pulled Takamiskari down at the center of the ring after the two wrestlers exchanged a series of arm thrusts to the face.
Musoyama, who needs a winning record to maintain his ozeki status in the next tourney, faced little resistance when bulldozed winless komusubi Iwakiyama out to pick up his fifth straight win and improve to 5-2.