While Urawa coasted against some generous defending by Omiya on Saturday, title challengers Sagan Tosu and Kashima Antlers could only manage 2-2 home draws to lose ground in the final match before the league stops for the international break.
Japan host Uruguay on Friday before taking on Venezuela four days later as new head coach Javier Aguirre takes charge of the Asian champions for the first time.
There was no place in the Mexican's all changed squad for any Urawa outfield players despite their strong showing as they continued their push for a first league title since 2006.
Tsukasa Umesaki slid in to open the scoring midway through the first half for the high-flying Reds, with Shinzo Koroki and Ryota Moriwaki adding headed goals after some poor defensive work by the visitors.
Tomoya Ugajin notched a fourth on the hour mark after a swift break and some questionable goalkeeping by Omiya stopper Takashi Kitano as the home side picked up the three points to take their tally to 44 from 22 games.
"Despite what the final score says, this was anything but an easy night's work for us," Urawa manager Mihailo Petrovic told Japanese media.
"They played hard and we made a few mistakes. We showed how much we wanted to win this game right from the start, and the fact that we got the three points was a result of that."
The desire was in stark contrast to their opponents, who slumped to a fifth defeat in six matches and sit one place of the bottom of the standings in 17th, five points away from safety.
Manager Kiyoshi Okuma paid the price for the awful run when he was ditched by the club on Sunday and replaced by his assistant Hiroki Shibuya for the remainder of the campaign.
Urawa's lead at the top could have been bigger but for Ryota Hayasaka's stoppage time equaliser for Sagan Tosu as they grabbed a draw with Shimizu S-Pulse.
The hosts were leading 1-0 with 10 minutes to go after Kota Mizunuma's opener only to concede twice in seven minutes to almost toss away the game.
Kashima are third in the table four points back of Urawa after they blew a 2-0 halftime lead at home to eight-placed FC Tokyo.
Midfielder Yoshinori Muto, one of a handful of uncapped players called up by Aguirre, grabbed the equaliser for the visitors with three minutes remaining after a mix up between goalkeeper Hitoshi Sogahata and defender Kazuya Yamamura.
Aguirre will also have been buoyed by the performance of another uncapped call up, with striker Yusuke Minagawa scoring the only goal as champions Sanfrecce Hiroshima overcame bottom side Tokushima Vortis to move up to ninth.