Brazilian midfielder Fernandinho scored both goals Sunday as Vegalta Sendai defeated Kashima Antlers 2-1 to hand the defending champions their first loss of the J-League season.
Fernandinho gave the hosts an early lead with a right-foot shot from the top of the area in the opening minute.
Kashima had Marquinhos sent off for unsportamanlike play in the 14th minute and Fernandinho doubled the lead with his second goal in the 61st minute.
Shinzo Kuroki pulled one back for Kashima with just over 10 minutes left in regulation, but the three-time champions couldn't find an equalizer.
Kashima remains one point behind Shimizu S Pulse which defeated Yokohama F Marinos 2-1 on Saturday to improve to 11 points in the J-League standings.
Forward Shinji Okazaki scored both goals for Shimizu, which continued its unbeaten start to the season.
It was a costly loss for Yokohama as midfielder Shunsuke Nakamura left midway through the first half with a bruised ankle.
Yokohama officials said Nakamura could miss Japan's friendly against Serbia on Wednesday.
Elsewhere, Shinji Kagawa scored twice as Cerezo Osaka beat Kyoto Sanga 3-1 to register its first win of the season.
Kagawa scored in the 31st and 52nd minutes and Cerezo secured the win when Ryuji Bando came off the bench and scored in the final minute of regulation.
Montedio Yamagata also picked up its first win of the season by edging Sanfrecce Hiroshima 1-0 after striker Yuzo Tashiro scored the decider in the 74th minute.
Igor Burzanovic scored twice to give Nagoya Grampus a 2-0 win at home over Vissel Kobe, while Albirex Niigata played out a scoreless draw with Omiya Ardija.
Robson Ponte and Yuki Abe scored in each half to give Urawa Reds a 2-1 home win over Shonan Bellmare. Urawa is also one point behind Shimizu in the standings.
South Korean defender Park Joo-ho scored a pair of goals as Jubilo Iwata defeated Gamba Osaka 4-3.