Mongolian Ama stunned compatriot Hakuho on Tuesday, leaving one man standing in sole possession of the lead at the Summer Grand Sumo Tournament.
With five days remaining and the adrenaline wafting to the rooftop, Bulgarian ozeki Kotooshu has taken the lead with a perfect 10-0 record, while Hakuho and rival yokozuna Asashoryu sit one off the pace at 9-1.
In the day's final bout, Hakuho was thrown off by a quick "henka" sidestep by Ama (6-4) and never fully recovered as the diminutive sekiwake poured on the pressure before sending the yokozuna toppling into the ringside seats with a powerful overarm throw at Ryogoku Kokugikan.
Kotooshu, meanwhile, gobbled up Kakuryu (3-7) before the No. 3 maegashira ever knew what hit him, leaning inside from the left before shoving his opponent down from the rear for a comfortable win.
Kotooshu, who entered the 15-day meet facing relegation, has been in scintillating form, posting his most impressive winning streak since, going 12-0 as a sekiwake at the 2005 Autumn Basho.
The ozeki, who will face his biggest test against Asashoryu on Wednesday, is in the hunt for his first Emperor's Cup.
Asashoryu was all business against Kotoshogiku, who beat him at the spring meet in March.
After getting a right-handed grip on Kotoshogiku (6-4), it was mere seconds before Asashoryu drove the sekiwake over, giving his opponent a cheeky shove for good measure.
