FC Seoul maintained the pressure on K-League leaders Jeonbuk Motors with an emphatic 6-0 win over Busan I Park.
Seoul, the 2010 champions, are pushing to secure automatic qualification for next season s AFC Champions League and remain in second place following their impressive display against seventh-placed Busan.
Jeju United were also 6-0 winners over the weekend, outplaying mid-table Chunnam at home.
Jeonbuk accounted for Gangwon 2-1, while Ulsan moved into third after defeating Gwangju by the same score.
Ulsan s victory saw Suwon drop down to fourth after the Bluewings could only draw 0-0 away to Daegu.
In other matches, Pohang Steelers defeated Incheon United 2-1 and Daejeon Citizen played out a 2-2 draw with Sangju Sangmu in a battle between the league s lowest-placed team.