NAGOYA, Japan — Hakuho overpowered Hokutoriki on Thursday to stay tied for the lead with Mongolian compatriot Ama at the Nagoya Grand Sumo Tournament.

Grand champion Hakuho got an inside grip on the belt of Hokutoriki and lifted the winless No. 2 maegashira out over the ridge to improve to 5-0 at Aichi Prefectural Gymnasium.

In another key showdown, Mongolian grand champion Asashoryu was upset by No. 3 maegashira Tochinonada in the day's final bout, which required a ringside meeting of the judges to determine the outcome.

Both wrestlers fell out simultaneously and the referee ruled in favor of Tochinonada. Replays showed that Tochinonada touched the dirt surface first, but the judges ruled Asashoryu was already out of the ring by that time.

Asashoryu, who, fell to 3-2 while Tochinonada has the same record in the 15-day tourney.

In other major bouts, sekiwake Ama improved to a perfect 5-0 when he overpowered Chiyotaikai and shoved the ozeki out over the straw ridge. Chiyotaikai, who needs a winning record to maintain his ozeki rank, dropped to 3-2.

Bulgarian ozeki Kotooshu got both arms around Wakanoho and waltzed the winless top maegashira out to improve to 3-2.

Kotooshu came into the Nagoya tournament looking for promotion to grand champion but with two early losses already, he can put his hopes on hold.