Ulsan Horangi kicked off the 2011 K-League championship play-off series with a surprise 3-1 win over FC Seoul at Seoul World Cup Stadium. Ulsan finished sixth in the league but now face the winners of tomorrow's clash between Suwon Bluewings and Busan I'Park on Wednesday to see who moves on to face Pohang Steelers in the semi-final.

The visitors took the lead after 17 minutes. Seoul goalkeeper Kim Yong-Dae failed to hold on to a corner and Kwak Tae-Hwi was on hand to steer the loose ball into an unguarded net. Ulsan then extended their lead ten minutes before the break. Yong-Dae came to collect a cross but was beaten to the ball by Kim Shin-Wook, who headed home.

The second-half started with Seoul pressure and 13 minutes in, Dejan Damjanovic headed the hosts back into the game but straight from the kick-off, Ulsan restored their two-goal advantage. Seol Ki-Hyeon broke free down the right and his cross was met with a diving header from Koh Sul-Gi. Seoul then hit the bar and had a goal ruled out for offside but in the end, were unable to get back in the game.

"Our players saw in the media that we had been written off and that motivated us," said Ulsan coach Kim Ho-Gon. "We defended well and attacked well. All the players gave their all. We know that in the play-offs every game is tough and we were ready for that."

The defeat ends Seoul's hopes of defending their league title. "The players did their best," said caretaker coach Choi Yong-Soo. "It was one of those games and congratulations to Ulsan on their win."