John Obi Mikel insists Nigeria must 'go back to the drawing board' following their 2-0 World Cup defeat to Croatia, but still harbours hopes the Super Eagles can progress from Group D.
An own-goal from Oghenekaro Etebo and a penalty from Luka Modric secured the points for Croatia from a turgid contest in Kaliningrad on Saturday, without Nigeria ever looking likely of mounting a comeback.
And former Chelsea midfielder Mikel, who captains Gernot Rohr's side, acknowledged Nigeria must improve ahead of their clash with Iceland on Friday.
"We have to play better. I think we can play better, we can do better," Mikel told reporters.
"It's difficult to say I think. We have to go back to the drawing board and see what we can do better, together as a team.
"It's not easy playing against these fantastic players, European players, they can hurt you in any given time. We know that, but we have to do better."
However, despite Nigeria's inefficiencies, Mikel is confident that progression from Group D is still possible, citing that Argentina's unexpected draw with Iceland has provided the Super Eagles with a lifeline.
"Why not? We believe. That's why we're here," the skipper added.
"That's why we came here. We have two more games to play. Argentina drew today so I think this is a bit better for us.
"Next game, we have to go and try to win the game. If we do that, we're back in it again."