Kwak, who only returned to the squad last November following a lengthy lay-off with a similar injury, twisted knee ligaments during a challenge in the first half and was carried off on a stretcher.
Coach Huh Jung-moo is set to call up either Suwon Bluewings defender Kang Min-Soo or Hwang Jae-Won of Asian champions Pohang Steelers to take Kwak's place in his 23-man World Cup squad.
"Kwak will need at least four weeks to recover from twisting a ligament in his left knee,'' said media officer Lee Won-Jae.
South Korea complete their preparations against European champions Spain on Thursday ahead of their opening game against Greece in Group B on June 12.
Source : http://soccernet.espn.go.com/world-cup/story/_/id/791455/ce/uk/?cc=4716&ver=global