Kotooshu's recent struggles have turned out to be just what the doctor ordered.
Bulgarian ozeki Kotooshu defeated Hakuho in convincing fashion Thursday, disposing of his second yokozuna in a row to maintain his perfect 12-0 record as the sole leader with just three days remaining at the Summer Grand Sumo Tournament.
Asashoryu, meanwhile, who fell to Kotooshu a day earlier, dropped to a stunning third defeat at the hands of ozeki Chiyotaikai to all but ruin his chance of winning his 23rd Emperor's Cup at the Tokyo meet. Hakuho sits at 10-2, two off the pace.
Kotooshu entered the 15-day meet facing demotion but has been in scintillating form, posting his most impressive winning streak since going 12-0 as a sekiwake at the 2005 autumn basho.
In the day's final at Ryogoku Kokugikan, Kotooshu came flying out of the blocks, getting his left hand inside on Hakuho's mawashi before muscling the Mongolian yokozuna over the edge in a frontal assault.
Kotooshu took a major step forward in his bid to become the first ever European grappler to win the title while Hakuho can only hope for a miracle to rope in his seventh career crown and first in two basho.
Asashoryu, who appears to have lost all his concentration, went sprawling to the dohyo surface when Chiyotaikai (4-8) sidestepped after the faceoff in the penultimate bout.
Kaio made short work of Mongolian Kakuryu (4-8), plowing out the No. 3 maegashira to pick up his seventh win but fellow ozeki Kotomitsuki (6-6) was sent backpedaling in a lopsided affair against sekiwake Ama, who improved to an 8-4 mark.
Russian maegashira youngster Wakanoho (5-7) steamrolled over Kisenosato, driving the giant-killing komusubi out in a textbook frontal force out.