Tamawashi stayed one win clear of his nearest rivals at the Autumn Grand Sumo Tournament on Friday after comfortably beating fellow title contender Nishikifuji.
The No. 3 maegashira from Mongolia, who won his only Emperor's Cup in January 2019, improved to 11-2 by thrusting down No. 10 Nishikifuji (9-4).
No. 4 Takayasu and No. 8 Hokutofuji are second on the leaderboard at 10-3 after winning their respective matches on Day 13 of the 15-day competition at Ryogoku Kokugikan.
Veteran former sekiwake Tamawashi stayed in control against Nishikifuji, deflecting his initial charge and shoving him to the clay with a hand to the back of the neck.
Former ozeki Takayasu made short work of komusubi Kiribayama (7-6), while former komusubi Hokutofuji snapped a three-match losing streak by beating No. 1 Tobizaru (9-4), who also started the day tied for second.
Sekiwake Wakatakakage, a first-time champion in March, stayed in the hunt at 9-4 by slapping down ozeki Takakeisho (8-5).
Rising star Hoshoryu (7-6) closed in on a winning record in his first tourney at sekiwake after throwing No. 4 Nishikigi (5-8), while fellow sekiwake Daieisho (5-8) is set for demotion following his eighth loss against No. 6 Wakamotoharu (8-5).
Ozeki Mitakeumi (4-9), who will be demoted to sekiwake for the next meet, and Shodai, who will compete as a demotion-threatened kadoban ozeki, squared off in the day's penultimate bout, with Shodai (3-10) winning by push out.