Hakuho barged out Hokutoriki to maintain his unbeaten start but yokozuna rival Asashoryu crashed to a shock second defeat at the Nagoya Grand Sumo Tournament on Thursday.
Hakuho put on another masterclass at Aichi Prefectural Gymnasium, slipping inside Hokutoriki's right arm to take control and barge the winless maegashira over the ridge.
Hakuho shares the lead at 5-0 with Mongolian sekiwake Ama, who stunned relegation-haunted ozeki Chiyotaikai. Overnight co-leader Tochiozan dropped into a seven-way tie for second after getting bashed up by Yoshikaze (2-3).
In the day's final bout, Asashoryu was unable to keep up the pressure on the leaders and slumped to a second defeat after being sent flying by third-ranked maegashira Tochinonada (3-2).
Both Hakuho and Asashoryu are looking to rebound from disappointing campaigns at the summer basho in May. The Mongolians sparked controversy after they nearly traded blows following their match on the final day of the meet and both finished with subpar marks of 11-4.
Asashoryu is shooting for his 23rd Emperor's Cup while Hakuho seeks his first championship victory since beating Asashoryu on the last day of the New Year meet.
Meanwhile, down but not out, Bulgarian ozeki Kotooshu looked back to his best after a dreadful start to the tournament, calmly lifting out Russian Wakanoho (0-5) to move into the winning column at 3-2.
Kotooshu saw his hopes of winning promotion to sumo's top rank of grand champion shattered after losing twice in the first three days of the 15-day meet. He was seeking promotion after becoming the first European wrestler to win the Emperor's Cup.
