Ozeki Kisenosato was tripped up to a first defeat at the hands of Aminishiki, while yokozuna Hakuho dispensed with Bulgarian Aoiyama in the blink of an eye on the fourth day of the Nagoya Grand Sumo Tournament on Wednesday.
Hakuho, who is seeking his 23rd career title and first in two meets, improved to 4-0 as the favorite among six early leaders, including ozeki pair Harumafuji and Baruto.
Kisenosato was slow at the tachiai and was immediately shoved backward by Aminishiki, who was pulled over the edge by the ozeki at the last moment.
The referee raised the gumbai flag for Kisenosato at first glance, but video footage later confirmed that the ozeki's foot had broken the barrier first for a loss.
"I just wanted to make strong contact. I had a great tachiai," said Aminishiki, who got his first win. "I didn't think I'd make it to the interview room this tournament. I just want to continue fighting good sumo."
Expectations are high that Kisenosato will become the first Japanese wrestler to win a championship since Tochiazuma achieved the feat at the 2006 New Year meet, but the Naruto stable wrestler was lacking any venom in his bout against Aminishiki.
In the day's final at Aichi Prefectural Gymnasium, Aoiyama hit the yokozuna hard at the clash but there was nothing that followed as Hakuho quickly swatted the No. 2 maegashira to the dirt.
Hakuho improved his record to 12 straight wins against first-time opponents.
"I didn't actually get nervous," said Aoiyama, who slipped to 1-3 and faces compatriot Kotooshu on Thursday. "It was a good learning experience."
Ozeki Kotooshu (3-1) had no problem dispatching with Shohozan (1-3), wrangling his opponent over in a textbook frontal force out.