After a solid victory over Beijing Guoan in the Asian Champions League, Ulsan Hyundai are on track to progress to the next phase.
Coach Kim Ho-gon said the win at home was vital as a loss would have had them in trouble.
"Beijing are a good team and it was a very tough first win for us. If we had lost today then we could have said goodbye to any chances of making the second round," said Kim.
"Compared to when I arrived at Ulsan before the start of the season, we are improving. We know what we have to do and with time, I think that we will keep getting better."