A late header from substitute Lee Se-ju gave Incheon the points against the high-flying capital club.

The result was a deserved one as the hosts made most of the running but it took Incheon until four minutes from time to break the deadlock.

The Seoul defence allowed a deep cross from Jeon Jae-ho to bounce in the box and Lee nodded the ball into the top corner of the net to give Incheon a fourth successive win.

United move into sixth while Seoul stay in fourth, three points behind leaders Ulsan Horangi who won the previous day.

"Most important today was the win," said Incheon coach Ilja Petkovic. "We are now in the play-off spots and I will be happy if we are still there at the end of the season."

Seoul coach Nelo Vingada has vowed to work hard during the break to ensure his players are back to their best when the season resumes in July.

"We didn't play well. This is the most disappointing game of the season," he said. "We have a break now and we will work hard in training over the next few weeks."

Busan I'Park dropped out of the top six after being held to a 1-1 draw at home to Daejeon Citizen.

Yoo Ho-joon put the hosts ahead seven minutes before the break only for Park Yong-ho to salvage a point for the visitors deep into injury time.

In the day's other game, Gwangju Sangmu defeated Gangwon FC 1-0.