Komusubi Nishikigi defeated grand champion Terunofuji in one of three major upsets on Sunday, March 10, the opening day of the Spring Basho.
In the day's final bout, Nishikigi was pushed back to the edge but held his ground and got both arms around his opponent before shoving the stunned yokozuna out over the edge.
"I was able to get a position on him after the face-off and my preparation paid off," Nishikigi said.
Terunofuji is hoping to win his 10th Emperor's Cup but didn't get the start he wanted.
The lone grand champion captured his ninth Emperor's Cup in the January tournament when he went an impressive 13-2 and then defeated then-sekiwake Kotonowaka in a playoff.
In 2023, Terunofuji won the May tournament but then had to sit out the last three tournaments of the year. Winning back-to-back basho may be a tall order for the 32-year-old Mongolian who has battled a series of injuries in recent years.
Kotonowaka Triumphs in First Bout as an Ozeki
In other major bouts, Kotonowaka madę a winning start to his ozeki career when he swatted down No 2 maegashira Atamifuji immediately after the face-off.
It was an easy Spring Grand Sumo Tournament win for Kotonowaka, who is the son of former sekiwake Kotonowaka Terumasa and grandson of former yokozuna Kotozakura.
He was promoted to sumo's second-highest rank of ozeki after notching 33 wins over the previous three tournaments.
In the day's first big upset, top maegashira Ura came in low at the face-off. Ura then got a hand on the back of the head of Hoshoryu and hauled down the Mongolian ozeki to the delight of the sold-out crowd at Osaka Prefectural Gymnasium.
The upsets continued in the very next bout when komusubi Abi used a double-handed thrust to the neck before pulling down ozeki Kirishima.
It was not a good start for the two Mongolian ozeki, who are aiming to contend for the title in the 15-day basho.
Ozeki Takakeisho, who needs eight wins to maintain his rank, calmly swatted down top maegashira Asanoyama to kick off his campaign on a winning note.
Successful Sekiwake Return for Wakamotoharu
Wakamotoharu, returning to the rank of sekiwake for the first time since November 2023, opened with a win when he used a series of powerful arm thrusts to shove out No 3 maegashira Oho.
Sekiwake Daieisho wasn't as fortunate as he was slapped down by No 2 maegashira Meisei for an opening-day loss.
Further down the ranks, No 17 maegashira Takerufuji won in his debut in the elite ranks when he spun Daiamami around after the face-off and shoved the 16th-ranked maegashira out.
Takerufuji needed only nine tournaments since his professional debut to reach the top division, tying the record with former komusubi Jokoryu.
Former ozeki grapplers Shodai and Mitakeumi, both now fighting as No 10 maegashira, posted opening-day wins over fellow rank-and-filers Kotoshoho and Ichiyamamoto, respectively.