(Okinoumi (L) takes out Shimanoumi)

TOKYO - A mishap involving a referee left maegashira Okinoumi in the sole lead of the Autumn Grand Sumo Tournament on Friday, the sixth day of competition.

No. 8 maegashira Okinoumi started the day at Ryogoku Kokugikan with a 5-0 record along with sekiwake Takakeisho. But Takakeisho lost when he appeared to have been accidently tripped by referee Tamajiro Kimura.

Yokozuna Kakuryu (4-2) ended the surprising day when he was shoved out by No. 3 Daieisho (2-4).

Having lost all four of his previous bouts against Kakuryu, Daieisho doggedly fended off the Mongolian grand champion, who is seeking his second straight championship after winning July's grand tournament in Nagoya. It was the maegashira's first career win over a yokozuna in 11 career bouts.

"This is the happiest I've been up until now," the 25-year-old said of his first kimboshi, a win by a maegashira wrestler over a yokozuna. "This is the biggest confidence boost."

Takakeisho, looking for four more wins to regain his ozeki status for November's Kyushu tournament, lost his footing after the referee got in his path.

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As komusubi Endo pressed forward, Takakeisho appeared to step backward onto the edge of the referee's left foot. When the referee yanked his foot out of the way, the sekiwake's right foot slipped out from under him and he crashed to his first defeat.

"I don't know what happened," Takakeisho said. "I wasn't under pressure. What's done is done."

"I came here hoping to win every bout, but it's just not that easy."

Endo improved to 5-1, his only loss coming against Kakuryu on the opening day of the 15-day tournament.

Moments later, in the match between ozeki Goeido and No. 2 Asanoyama, Kimura gave the wrestlers an extra-wide berth as he shifted his position. In the process, the referee tripped on the straw bales and went tumbling out of the ring. Asanoyama threw Goeido, leaving both wrestlers with 4-2 records.

The referee suffered abrasions on the right side of his forehead but asserted he would attend to his duties on Saturday.

"I can walk, so I'll be fine," Kimura said.

Okinoumi earned a solid win over No. 6 Shimanoumi (2-4). The 34-year-old Okinoumi seized his opponent's right arm on his initial charge. Shimanoumi spun and tried to wriggle free, but Okinoumi lowered his head, charged forward and drove his opponent from the ring.

Ozeki Tochinoshin (2-4) followed Goeido to the ring and suffered his fourth defeat, getting shoved out by No. 4 Tamawashi (4-2). With a different referee in charge, the Georgian ozeki was originally ruled the winner, but that decision was overturned upon video review.

Referee Inosuke Shikimori, who took Kimura's place on the raised ring, later apologized to Japan Sumo Association Chairman Hakkaku.

"He (Hakkaku) encouraged me to do my best," Shikimori said.

Each ozeki needs 10 wins to avoid relegation to the sekiwake rank in November following two straight grand tournaments with fewer than eight wins.

Sekiwake Mitakeumi (5-1) won his fifth straight bout, shoving No. 1 Hokutofuji (1-5) straight from the charge with thrusts to the shoulder and neck.

On Saturday, Okinoumi will take on No. 6 Myogiryu, who improved to 5-1 on Friday. Okinoumi holds an 11-10 edge in their 21 career bouts.

Among the wrestlers who improved to 5-1 was 98-kilogram Enho, who proved too pesky for No. 13 Kagayaki (3-3).

With a 65-kg weight advantage, Kagayaki struggled to keep his balance while pressing forward against the crafty No. 11. As a result Enho was twice able to scamper backward, escape and attack Kagayaki from the side.

As Enho lunged for his right leg, Kagayaki tried to dance away but lost his balance, allowing the smaller wrestler to shove him out.