Goyang Hi pushed K-League champions Jeonbuk all the way before succumbing to an Edu goal in the first half of extra-time. Jeonbuk weren’t the only top team to face difficulties against lower league opposition as Seoul Eland took Ulsan to penalties before eventually losing the shoot-out. Pohang, Seoul, and Jeju United all made light work of their opponents. Gangwon were the only lower league side to knock out a K-League opponent, beating Busan 3-2 away from home. Yeungnam University reached the fifth round after beating Sangji University 2-1 while Chungju and Cheonan City also made it through to the fifth round. Three matches are still left to be played in the fourth round, the biggest of which is Suwon Bluewings against Jeonnam Dragons on the thirteenth of May.