Midfielder Yuji Yabu scored the only goal in Kawasaki Frontale's 1-0 win over Gamba Osaka, lifting his side to second place in the J.League standings.
The goal came in the 32nd minute after Brazilian striker Renatinho received a long pass from behind and sent a cross from the left to the goalmouth, where Yabu flicked in.
Osaka controlled most of the game, but Kawasaki goalkeeper Eiji Kawashima was the hero of the day. He stopped a penalty by Japan international midfielder Yasuhito Endo in the 53rd minute, and saved a shot on goal from a free-kick three minutes later.
"We had expected Osaka to play aggressively, but this is a game we needed to win in order to take the championship," said Kawashima.
The victory was Kawasaki's second in a week over Osaka, after they came from behind to beat them 3-2 in round 16 of the AFC Champions League.
After six consecutive wins in the J.League, Kawasaki now have nine wins, three draws and three defeats for 30 points, trailing defending champions Kashima Antlers on 38 points. They are followed by Albirex Niigata and Urawa Red Diamonds on 28 points each.
In Wednesday's only other J.League game, Kashima beat Nagoya Grampus 3-0 with Shinzo Koroki, Takuya Nozawa and Brazilian striker Marquinhos on target.