Greece coach Otto Rehhagel has warned his players they cannot afford another lapse in concentration if they are to keep their World Cup dreams alive.

The Greeks opened their Group B campaign with a 2-0 defeat to South Korea and the coach admits their hopes were blown out of the water inside seven minutes when they failed to pick up Korean defender Lee Jung-soo as he met Ki Sung-yueng's free-kick to open the scoring.

The 71-year-old German said: "Basically, we played into our opponents' hands from the seventh minute. The defenders failed to head it away and South Korea took full advantage."