TOKYO, Jan. 16 - A big upset marked the fourth day of the spring professional sumo tourney when Azumafuji, new "yokozuna," suffered his first defeat in the current tournament at the hands of Mitsuneyama, fighting "maegashira," at the specially constructed Kokugikan in Hama-cho Park, here yesterday.
    By pushing out Terunobori, tricky "maegashira," on that day, Masuiyama, new "ozeki," maintained his winning streak since the opening day. He is now the only undefeated wrestler among the high ranking grapplers in both the East and West camps.