Jeonbuk Motors' status as K.League title favourites is under threat as they face a steeper hurdle than their rivals in round 29 of 33.
The leaders have dropped points in three of their last four matches and will be without influential midfielder Kim Nam-il for Wednesday's visit of fourth-placed Jeju United, who have only suffered one defeat in their last four trips to a ground affectionately known as 'Fort Jeonju'.
With second-placed Pohang Steelers playing second-bottom Gyeongnam and third-placed Suwon Bluewings at home to lowly Incheon United, Jeonbuk coach Choi Kang-hee has stressed that nothing shy of victory will suffice.
"We must win this match against Jeju in order to maintain pole position," he said. "We have a tougher test [than our rivals] but we're playing at home, so we have to go out there with a positive approach."
With Kim suspended, there will be added pressure on fellow veteran Lee Dong-gook to perform. The former Middlesbrough striker sits three goals clear at the top of the K-League scoring chart and was recently named in Uli Stielike's squad for his first match in charge of South Korea against Paraguay.
Pohang have won four and drawn two of their last six games away to Gyeongnam, who did nevertheless end a 10-match winless home run against Sangju Sangmu last time out.
It will only be a 'home' fixture on paper for Gyeongnam. They will, after all, leave their Changwon base to stage the match in Yangsan, which is much closer to Pohang.
Suwon, for whom defender Oh Beom-seok recently returned from military service, have won four and drawn two of their last six outings to move three points off the pace.
The four-time K.League champions have tasted victory in their previous two encounters with Incheon this season, scoring three times in each.
Incheon, however, can take confidence from claiming four points from their last two games, including a 2-0 victory at high-flying Jeju last time out.
A run of just one point from a possible 12 has dropped Seongnam level on points with the bottom two, leaving the record seven-time champions in danger of relegation for the first time.
They host a Jeonnam Dragons side who will hope Macedonian forward Stevica Ristic can continue the form that has brought five goals in eight games.
Busan I'Park, fresh from winning for the first time at home in 10 K.League games, host a Sangju Sangmu side just one point above them in a high-stakes relegation battle.