Incheon looked set to end their four-game winless streak as Park Tae-Min put the hosts 2-0 up in the 72nd minute, adding to Lee Chun-Soo's strike late in the first half.
But substitute Park Seong-Ho had other ideas and grabbed goals in the 77th and 90th minutes to keep Pohang a point clear at the summit of the Korean top flight.
Choi Kang-Hee's side have a one-point lead over third-placed Ulsan but have now played two games more.
Daejeon took the lead on the half-hour mark as Dong-Hyun Lee struck, but Bong-Jin Kim cancelled out that advantage prior to the break before Chun Jae-Ho's second-half double sealed the points for the visitors.
And in the weekend's final match, Jeju United won their third straight game as they earned a 1-0 victory against Chunnam Dragons.
