Both games were goalless at the end of normal time but Suwon City scored in extra time to defeat Daegu 1-0 while Daejeon Hydro & Nuclear Power did the same to Gangwon.

Meanwhile, FC Seoul struggled at home to Mokpo City but finally progressed after a penalty shootout.

Hyun Yong-min gave Seoul the lead in the final minute of extra time only for the visitors to equalise immediately to take the game into the shootout, which Seoul won 4-3.

Elsewhere, K-League champions Jeonbuk Motors saw off the challenge of Jeonju University with a 5-0 win, helped by an Lim Sung-hyub hat-trick, while Asian Champions League holders Pohang Steelers defeated Chungju Hummel 5-1.

Suwon Bluewings beat Dankuk University 2-0 while Seongnam Ilhwa Chunma struggled to a 1-0 win over Yongin City.

Incheon United made it into the last 16 after a 2-1 win at Ansan Hallelujah, Chunnam Dragons thrashed Gimhae FC 6-2 and Ulsan Horangi triumphed 5-2 at home to Goyang Kookmin Bank.

Gyeongnam FC are second in the league and survived a scare at Changwon City to win 3-2 while Jeju United won 3-1 at Busan Transportation.

Busan I'Park defeated Incheon Korail 3-0 while Daejeon Citizen and Gwangju Sangmu made it past the respective challenges of Kyunghee University and Ulsan Mipo.