A last-minute Lee Sung-Hyun strike saw Jeonbuk Motors twice come from behind to win 3-2 at Daejeon Citizen as the Jeonju team went two points clear at the top of the K-League.
Hwang Jin-San put Daejeon ahead after 18 minutes and, although Lee Dong-Guk headed home the equaliser from a Choo Chul-Soon cross, Park Song-Ho restored the hosts' lead from the spot before the break after Huang Bowen brought down Kim Sung-Jun.
Jeonbuk looked set for defeat with eight minutes remaining, but Lee Dong-Guk levelled once more and Lee Sung-Hyun netted in the final minute to complete a great week after the Jeonbuk side also reached the last eight of the AFC Champions League.
"It was a very tough game but I am satisfied with the fact that we are back on top of the K-League," said Jeonbuk coach Choi Kang-Hee. "Daejeon played well in the first half but we used our substitutes well and came back in the second."
Suwon Bluewings also reached the last eight in Asia but crashed to a fifth defeat in their last six domestic games, losing 2-1 at Incheon United.
Jang Won-Seok fired home a second-minute free-kick for the hosts but, 13 minutes later, Yeom Ki-Hun curled a shot past the Incheon goalkeeper.
Just after the half-hour, Uzbekistan international Timur Kapadze converted what turned out to be the winner from the penalty spot.
Fellow Champions League quarter-finalists FC Seoul crashed to a 2-0 defeat at Seongnam Ilhwa Chunma, the hosts' second win of the season.
Cho Dong-Keun broke the deadlock with 15 minutes remaining and Kim Jin-Yong sealed the win soon after.
Elsewhere, Gyeongnam were held to a 1-1 draw at home to Jeju United. Brazilian striker Jair put Jeju ahead in the first half while Luke DeVere earned a point for the hosts in the second.