Coach Gernot Rohr's Super Eagles -- who brought the youngest squad to Russia, with an average age of around 25 years of age -- have now won just one of their past 13 games at World Cups.
Nigeria reached the knockout phase at the 2014 World Cup, but slipped to a 2-0 defeat in their Group D opener against Croatia in Kaliningrad, courtesy of an Oghenekaro Etebo own-goal and a Luka Modric penalty.
Their side, including 19-year-old goalkeeper Francis Uzoho, were almost unrecognisable from the team beaten by France in the last 16 four years ago.
"Sometimes we were a little bit naive on set pieces but we will work on it," said Rohr.
Iceland are buoyant after what their coach Heimir Hallgrimsson described as a "schoolbook example" of how to defend against Lionel Messi's Argentina.
Messi complained that "Iceland didn't want to play" but the Nordic minnows, playing in their first-ever World Cup, were unimpressed by the criticism.
"Maybe he would have been happier if we had played attacking football and lost 5-0. People can have their opinion about it but we really don't care," said goalkeeper Hannes Halldorsson.
The Nigeria game in Volgograd will be "a bit more open," said the 34-year-old 'keeper, whose string of saves, most notably from a Messi penalty, kept the 2014 finalists at bay.
"Nigeria will be difficult to beat. They are fast and more direct than Argentina. It will be a different game in many ways," he added.
Rohr believes his team could still make it out of a highly competitive group.
"We are only one point behind (Iceland) and all is in our hands, so let's be positive. Let them learn from this defeat (against Croatia) and try to do better," said the former Bordeaux coach.