Pohang Steelers kept their K-League title hopes alive with a 2-1 win over Jeonbuk Motors on Saturday.
The hosts went into the game five points behind championship round leaders Ulsan, but have now narrowed the gap to two following a slender home victory against AFC Champions League chasers Jeonbuk.
Pohang opened up a two-goal lead inside the first 22 minutes thanks to goals from attackers Kim Seung-Dae and No Byung-Jun and, although Brazilian midfielder Leonardo pulled one back for Jeonbuk 10 minutes before the break, the home side were able to hold on to claim a much-needed victory.
Ulsan are still favourites for the title as they have a game in hand over Pohang, but Jeonbuk's defeat afforded Seoul the chance to gain ground in the race for the final Champions League spot.
However, it was an opportunity they failed to seize, the capital club requiring an injury-time equaliser to rescue a 2-2 draw with Incheon United.
Incheon looked to be on their way to victory when second-half goals from Han Gyo-Won and Park Tae-Min put them 2-1 ahead following Mauricio Molina's opener for Seoul.
But the hosts ensured a share of the spoils when forward Sergio Escudero struck in the 91st minute.
Elsewhere, Busan I'Park overcame Suwon Bluewings 1-0.
In the relegation round, Daejeon Citizen kept their hopes of survival alive with a 1-0 win against Seongnam, with the bottom-placed side earning their fourth straight win thanks to a strike from Hwang Ji-Woong.
Still, Daejeon have work to do if they are to stay up, after fellow strugglers Daegu and Gangwon - who have played a game less - also recorded victories.
Daegu avoided a third consecutive defeat as they won 2-1 at Jeju United, with Cho Hyung-Ik and Hwang Soon-Min securing the points despite Yoon Bit-Garam's late goal for the hosts.
Gangwon sit three points ahead of Daegu following their 2-1 success over Gyeongnam, which was clinched through goals from Choi Jin-Ho and Jin Kyung-Sun.