The Koreans led 2-0 inside the first 10 minutes in the sodden conditions at Al-Gharafa Stadium as Ji Dong-won scored the first of his two goals with a header after keeper Paul Subrata failed to deal with Lee Chung-yong's cross.
The hosts wanted a penalty after for a challenge on Chung-Yong Lee by Jamie Carragher, and they were appealing again when Paul Robinson's left-wing cross appeared to brush the same defender's arm.