The Slovenia striker got in front of the Gamba defence to tap home left back Tomoya Ugajin's cross and send the majority of the 53,000 crowd at Saitama Stadium home happy.
Saturday's victory, their first over their rivals in nine years, maintained Urawa's unbeaten start to the season and gave them a three-point cushion at the top of the table after nine matches.
"We wanted this win more than our opponent and I think we deserved it," Ljubijankic told Kyodo news agency.
"As a striker, you have to be patient for this one chance. My part was easy, the cross was perfect and I was just in the right place at the right time."
FC Tokyo moved a point ahead of Gamba into second place after coming from behind to beat Kawasaki Frontale 2-1 in another top-of-the-table clash on Saturday.
Midfielder Yoshinori Muto, who has been linked with a move to English club Chelsea, rose unmarked to head home the winner from an 87th minute corner.
Sanfrecce Hiroshima's 2-0 home win over Vegalta Sendai moved them up to fourth, while Nagoya Grampus beat Shonan Bellmare 3-0 and Kashiwa Reysol drew 0-0 with Shimizu S-Pulse.
(Reporting by Nick Mulvenney; Editing by John O'Brien)
Share
