Terunofuji sentenced Mongolian yokozuna Hakuho to a shock first defeat at the Spring Grand Sumo Tournament on Friday to keep his title hopes alive with two days of the 15-day basho remaining.
Hakuho could have sewn up a 34th career championship with two days to spare by beating Terunofuji (11-2), but the newly promoted sekiwake had other ideas in the day's finale at Bodymaker Colosseum.
Terunofuji shrugged off a series of slaps before both wrestlers went at it to gain control of the belt.
But the sekiwake went for broke and shook off an attempted leg trip to knock the yokozuna out of the ring and claim his first win in the four career meetings between the two.
Hakuho, who lost for the first time in 37 bouts, still holds a one-win lead over Terunofuji and can secure the championship if he beats Kisenosato on Saturday and Terunofuji loses to Ichinojo.
Also in the upper ranks, yokozuna Harumafuji choked Kisenosato with a throat grip and promptly marched the ozeki out for his 10th win. Kisenosato suffered his fifth loss.
Goeido (7-6) was given rapturous applause from home fans as the Osaka-born ozeki came through a tough contest to bump out Georgian No. 4 maegashira Tochinoshin (6-7) and close in on a winning record.
But Kotoshogiku came a cropper in the following bout as Toyonoshima forced the ozeki out to secure a majority of wins. Kotoshogiku dropped to 7-6.
Komusubi Myogiryu moved into the winner's column at 7-6 when he barged out Mongolian behemoth Ichinojo (8-5).
In earlier bouts, No. 12 maegashira Chiyootori moved his win total into double digits by pushing Chinese-born grappler Sokokurai (8-5) out from behind.
Georgian bruiser Gagamaru also improved to 10-3, thanks to an oshidashi win over sixth-ranked Brazilian Kaisei (5-8).