wrestler of grand champion quality without the title
Sumo term for a wrestler whose ability is on par with a yokozuna but who has not been promoted to that rank.
He was called a muroi-rikishi and had ability comparable to a yokozuna.
横綱 is the highest rank in sumo, while 無類力士 refers to a wrestler of that caliber who has not attained the rank.
大関 is the second-highest rank; a 無類力士 is typically an 大関 or lower-ranked wrestler with yokozuna-level skill.
Compound of 無類 (むるい, 'peerless, unparalleled') and 力士 (りきし, 'sumo wrestler'). The exact origin is uncertain, but it is a sumo-specific term.