Republic of Korea claim Football first
feature, Headlines, London Games, photo 03:43
Japan enjoyed plenty of possession but found it tough to break down a well-organised Korean defence.
Republic of Korea captain Koo was heavily involved from the off and had a penalty appeal waved away when he went down far too easily with Hiroki Sakai in close attendance.
It took almost half-an-hour for the first shot on target, with Jung Sungryong unconvincingly parrying Hiroshi Kiyotake's low shot.
Sakai headed over from a corner for Japan, but it was Republic of Korea who took the lead when Park seized on a poor defensive header to brilliantly turn Daisuke Suzuki and fire low beyond Shuichi Gonda.
Yuki Otsu crafted a great chance to level early in the second half, but he scuffed his shot after neat interplay with Keigo Higashi.
And the miss was punished a few seconds later when Sunderland's Ji Dongwon flicked on goalkeeper Jung's long ball downfield to allow Koo to shoot across Gonda into the net.
It was almost 3-0 just short of the hour but Gonda managed to tip Kim Bokyung's curling effort onto the post.
Japan pushed forward in search of a way back into the game, but their hopes of setting up a tense finish ended when Yoshida's header was ruled out for a block on Jung with three minutes to go.
