Pacesetters Gamba moved on to 50 points following their 4-0 away win over Vissel Kobe while reigning champions Nagoya climbed up to second, one point behind the leaders, after defeating 10-man Vantforet Kofu 4-1.
Takuya Takei's strike gave Gamba a half-time lead in Kobe before second-half efforts from Kim Seung Yong, Lee Keun Ho and substitute Takahiro Futagawa wrapped up the Osaka club's third successive victory.
Nagoya took advantage of Yokohama F. Marinos' draw yesterday by moving into the top two with a comeback victory in Toyota.
Mike Havenaar's ninth-minute opener for visitors Kofu was cancelled out by a fantastic running volley by former Japan forward Keiji Tamada in the 32nd minute, and two minutes later Australia forward Joshua Kennedy put the home side ahead with his league-leading 14th goal of the season.
Kofu were reduced to 10 men just before the break when Daniel was dismissed after conceding a free-kick, from which Jungo Fujimoto fired home from just outside the box to make it 3-1.
Fujimoto then completed the scoring with his second in the 69th minute.
Fifth-placed Kashima Antlers recorded the biggest win of the weekend as they thrashed rock-bottom Avispa Fukuoka 6-0.
Yuzo Tashiro and Yasushi Endo both netted braces while Daiki Iwamasa and Koji Nakata struck the other goals as Oswaldo Oliveira's side extended their unbeaten run to seven.
Elsewhere, fourth-placed Kashiwa Reysol fought back from 2-0 down to beat Kawasaki Frontale 3-2.
Kawasaki, who had lost their previous six games, looked on course for a rare win when Yusuke Takasa and in-form Brazilian forward Juninho netted twice in quick succession just after half-time, but Kashiwa hit back through goals from Masato Kudo and Junya Tanaka (two) to snatch the win.
Elsewhere, Cerezo Osaka beat Urawa Reds 3-1 thanks to two goals in the last three minutes from Takahiro Ogihara and Shu Kurata.