JOHANNESBURG, June 13 (Xinhua) -- Greece coach Otto Rehhagel admitted his team needed to improve and urged his players to "be brave and courageous enough" in the next games at the World Cup finals.

"We've got to improve a couple of things and be brave and courageous enough," Rehhagel said. "The South Koreans played very well, they used their chances, we didn't."

Greece lost 2-0 to South Korea in their World Cup opener. They only managed three shots on target and were outplayed throughout the game.

"We'll go back to Durban now and analyse what went wrong factually and soberly and try and improve for our next game." Rehhagel said.

Greece next play against Nigeria, who lost 1-0 to Argentina, at Bloemfontein on Wednesday.