Veteran midfielder Shunsuke Nakamura netted the only goal of the game on the stroke of half-time as Yokohama moved three points clear of defending champions Sanfrecce Hiroshima, who beat Vegalta Sendai on Saturday.
Urawa Red Diamonds also climbed back above Sanfrecce into second spot, two points behind Marinos, with a 2-1 home win over Kashiwa Reysol.
All three goals were scored in the opening 14 minutes, with Yosuke Kashiwagi's brace (five and 11 minutes) putting Urawa in charge before Masato Kudo halved the deficit.
On a weekend where all of the top four picked up victories and each of the bottom three suffered defeats, fourth-placed Kashima Antlers remained within six points of top spot with a 4-1 win over Kawasaki Frontale.
Shoma Doi (20), Yuya Osako (44), Kazuya Yamamura (56) and Yasushi Endoh (61) were on the mark for 2011 champions Kashima, with Gaku Shibasaki's 90th-minute own goal the only thing Kawasaki had to show for their efforts.
Fifth-placed Cerezo Osaka were unable to match their title rivals however as they went down to two late goals from Naoyuki Fujita (80) and Takashi Kanai (90) away to 14th-placed Sagan Tosu. Cerezo are now nine points behind Marinos with four rounds left.
At the other end of the table, Oita's defeat to Yokohama saw them stay seven points adrift of second-bottom Jubilo Iwata, who went down to an 80th-minute Genki Omae penalty at home to Shimizu S-Pulse.
Third-bottom Shonan Bellmare fell victim to a Kengo Kawamata-inspired Albirex Niigata as they also lost.
Kawamata's hat-trick, which included two penalties, put Albirex 3-0 up and although Shonan pulled late goals back through Ryota Nagaki and a Naoki Kawaguchi own goal, they could not avoid defeat.
In the other games, Marcus Tanaka's second-half brace (67 and 86) helped Nagoya Grampus Eight overcome a half-time deficit to claim a 2-1 win over Omiya Ardija, who had led through Milivoje Novakovic's 37th-minute strike, while Vantforet Kofu drew 1-1 with FC Tokyo.
Lowly Vantforet had been on course for their first league win in six games after taking a 28th-minute lead through Kazuki Hiramoto, but they were pegged back by an 80th-minute Yuhei Tokunaga equaliser.