Nigeria boss Lars Lagerback was left frustrated by officials following the 2-1 loss to Greece on Thursday.

The Africans had Sani Kaita sent off just after the half-hour mark when they were up 1-0 only to see Greece storm back and score twice to snatch a win.

Lagerback said he was unhappy with how the referees acted after the match as they could not find out why Kaita was given a red card.

"You go to the World Cup every four years and I am extremely disappointed," he said.

"The referees tell us to co-operate but you cannot speak to them after the game.

"They won't tell us why the player was sent off. We cannot have this dialogue.

"But I have to congratulate Greece. Now we need a favour from Argentina."