J. League heavyweights Urawa Reds slipped into the relegation places with five matches remaining after a 1-0 derby-day defeat to Omiya Ardija on Saturday.
Urawa, champion in 2006 and Japan's best-supported club, went into the match at Saitama Stadium having fallen into the bottom three by virtue of Ventforet Kofu's 4-0 win at Cerezo Osaka earlier in the day, and stayed there after an 84th-minute header from Brazilian striker Rafael gave Ardija the three points.
The result leaves Urawa one point adrift of Kofu, with Albirex Niigata two further ahead and a game in hand against Kawasaki Frontale on Sunday.