Seongnam, who won the Champions League in 2010, continue to struggle in their domestic league but will take on Suwon Bluewings in the cup final.

Sasa Ognenovski put Seongnam ahead six minutes before the break, scooping the ball home from close range after goalkeeper Shin Hwa-yong could only get a palm to Cho Dong-keon's cross.

Cho extended Seongnam's lead on the stroke of half-time, holding off two defenders to slot the ball past Shin from inside the penalty area.

With 25 minutes left, Dzenan Radoncic volleyed home a low shot to seal Seongnam's place in the final.

"It was a good win for us," said Seongnam coach Shin Tae-yong. "We want to get back into the Asian Champions League again."

Pohang boss Hwang Sun-hong said: "This was our worst performance of the season. We made a mistake with the first goal and that was at the root of the defeat."

Suwon won the cup last year and staged a superb fightback today to come from two goals down at home to Ulsan to win 3-2 after extra-time.

Seol Ki-hyeon lobbed Jung Sung-ryeong for the opening goal on the hour mark, and the former Fulham and Reading forward then shot home Ulsan's second with 16 minutes remaining.

Almost immediately, Stevica Ristic pulled a goal back for Suwon, and with eight minutes remaining Mato Neretljak headed home the equaliser.

Park Hyun-beom headed the winner after 20 minutes of extra-time.