Atsuki Ito's 21st-minute goal secured visiting Urawa Reds a 1-0 win over Vissel Kobe on Saturday, handing the early front runners their first defeat of the J-League top-flight campaign.
Urawa notched back-to-back league wins for the first time under new manager Maciej Skorza as they snapped Kobe's three-match winning streak to start the season.
Ito blasted from the edge of the area after Tomoaki Okubo headed Norwegian center-back Marius Hoibraten's long ball back into his path.
Hoibraten nearly doubled the lead when he headed into the woodwork from a corner kick midway through the second half at Noevir Stadium.
Urawa scored from their only shot on target, while Reds keeper Shusaku Nishikawa stopped all three from Kobe, still without Andres Iniesta following his return to Spain for a personal matter.
Kawasaki Frontale, last season's runners-up, continued their slow start, falling 1-0 away to promoted Albirex Niigata.
Ryotaro Ito scored in the 22nd minute for Niigata, who provisionally moved to second in the standings behind Kobe.