Amokachi, 25, injured the knee in training before Nigeria's opening game against Spain, which he missed, but played in the 1-0 win over Bulgaria.
The Besiktas striker, formerly of Everton and Bruges, was due to have captained the team against Paraguay on Wednesday until he aggravated the injury in the warm-up and team doctors have said that Amokachi's chance of recovering in time for further games is slim.
However, the Super Eagles are still brimming with confidence and say they will be playing for the whole of Africa in tomorrow's second-round match against Denmark, after the failure of Tunisia, South Africa, Morocco and Cameroon.
"The Danes should be ready for defeat," midfielder Finidi George said. "It's the only way to show the African presence and repay our fans."
For the second World Cup running Nigeria, who beat Spain and Bulgaria before losing 3-1 to Paraguay in a game which, for them, was academic, are the only African team to progress beyond the first round.Reuse content