Ozeki Tochiazuma suffered his first loss of the Summer Grand Sumo Tournament on Wednesday to find himself a pace behind the leaders only four days into the 15-day tourney at Tokyo's Ryogoku Kokugikan.
Tochiazuma, one of the favorites coming into the basho, got stung in a head-on collision with Tosanoumi and never recovered as the No. 2 maegashira ran the Tamanoi stable ozeki out of the ring.
The loss left Tochiazuma with a 3-1 record while Tosanoumi, who also upset ozeki Musoyama on Monday, joined the ozeki in the chase pack with his third win.
Yokozuna Musashimaru, meanwhile, posted an easy win over No. 3 maegashira Takanowaka to remain in the tournament lead with an unblemished record along with ozeki Chiyotaikai and No. 10 maegashira Kyokushuzan.
In the day's final bout, Musashimaru pummeled hapless Takanowaka (0-4) around the ring before finally swatting him out for his fourth win in a row.
Chiyotaikai got off to a running start against Toki (1-3) and back-pedaled the top maegashira out of the ring to hold onto his share of the tournament lead.
In an early bout between undefeated rank-and-filers, one-time komusubi Kyokushuzan, only 2-13 in March, twisted Dejima over with a well-timed headlock to move to 4-0 while the former ozeki was saddled with his first loss.
Also at the ozeki rank, Musoyama muscled out komusubi Tochinonada (2-2) for his third win and Kaio made quick work of Daizen, ramming the fourth-ranked maegashira out of the ring to even his record at 2-2.