Rank-and-file wrestler Nishikigi grabbed the outright lead at the Nagoya Grand Sumo Tournament after downing komusubi Abi to remain undefeated on Friday.
The No. 1 maegashira has compiled his spotless 6-0 record against a succession of top-ranked opponents, including all three sekiwake and lone yokozuna Terunofuji before his injury withdrawal from the 15-day meet.
Nishikigi started Day 6 at Dolphins Arena tied for the lead with No. 7 Takayasu and No. 13 Gonoyama, both of whom dropped to 5-1.
Former ozeki Takayasu was pushed out by No. 5 Onosho (2-4), while top-division debutant Gonoyama fell to another impressive newcomer, 19-year-old No. 17 Hakuoho (4-2).
Having debuted in the top division in May 2016, the 32-year-old Nishikigi is on track for promotion to the distinguished three sanyaku ranks below yokozuna for the first time in his career.
He absorbed a powerful opening barrage from pusher-thruster Abi (3-3) before shoving the komusubi across the ring and out.
New ozeki Kirishima, who missed the first three days of the meet with bruised ribs, improved to 2-2-2 in convincing fashion as he thrust down No. 2 Shodai (2-4).
Sekiwake Hoshoryu (5-1) demonstrated his impressive grappling technique to dispatch No. 3 Midorifuji (1-5) with an outside leg trip and remain one win off the pace.
The other two promotion-seeking sekiwake sit at 4-2 after mixed results on Day 6, with Wakamotoharu slapping down No. 3 Meisei (2-4) and Daieisho getting pulled down by komusubi Kotonowaka (4-2).