Returning after the league's mid-season break, Choi Kang-hee's men got back to winning ways with the success, which came on the road against a Busan outfit who continued their patchy form from before the FIFA World Cup.
The visitors moved in front in the 14th minute through Lee Jae-seong, and took a firm grip on proceedings three minutes after the break thanks to Han Gyo-won's strike.
Choi's side were able to see out the win from that point on, and they climbed to within two points of Pohang, who were held 0-0 at third-placed Jeju United, the hosts remaining four points behind their opponents as a result.
Fourth-placed Jeonnam Dragons will be ruing their lack of concentration after they let a two-goal lead slip at home to Seoul.
After moving into a commanding position with goals from Lee Jong-ho and Stevica Ristic in the opening 13 minutes, they allowed Osmar to pull one back before half-time.
Mauricio Molina levelled matters six minutes from time as both sides had to settle for a draw, with Jeonnam passing up the chance to move above Jeju into third.
There was a dramatic finish at the foot of the table, where second-from-bottom Sangju Sangmu claimed a last-minute winner in a 2-1 success at rock-bottom Incheon United.
Sangju went ahead courtesy of Lee Seung-hyun's penalty in the 54th minute, before Incheon looked to have rescued a point through Ivo's 83rd-minute equaliser.
They reckoned without Ha Tae-goon, however, who struck right at the end to earn the visitors their first win in six attempts.
Elsewhere, Seongnam drew 1-1 with Ulsan and the game between Suwon Bluewings and Gyeongnam ended goalless.
