Skipper John Obi Mikel and Victor Moses had to be cajoled into new roles as Rohr heeded the criticism that followed his side's opening Group D defeat by Croatia.

Obi Mikel was used as an attacking midfielder throughout Nigeria's qualifying campaign but a lacklustre showing in Kaliningrad meant he was asked to drop into a more defensive role against Iceland on Friday.

Moses, usually allowed to roam up front for Nigeria, was put to work as a right wing back against Iceland and after a tepid first half helped his side win three points by setting up the opening goal for two-goal hero Ahmed Musa.

"We changed our strategy and organisation, playing 3-5-2 with Victor Moses playing in the place where he plays at Chelsea and the captain came back to the position that he plays in Chia and used to play at Chelsea before," Rohr told reporters.

"I think it worked out well. They did this for the country, for the team. It was not easy to convince them but in the end they did it well. It gave us more space and the speed proved decisive for us."

But Nigeria were slow to get out of the blocks and became the first team not to have a shot in the first half of a World Cup game since South Korea against Algeria in Brazil four years ago.

"In the second half it was a different team because they realised at halftime that we had to do much more," Rohr said.

"We played against a very good team from Iceland who were better in the first half but did not score and we were better in the second half."

Nigeria's victory lifted them to three points and second in the group, behind Croatia who have qualified with six points.

They must avoid defeat against Argentina on Tuesday if they are to stand any chance of reaching the knockout stage.

Iceland, the smallest nation by population ever to compete in the World Cup, must defeat Croatia, who they beat in qualifying and have met several times recently, to have any hope of a fairytale run to the next stage.

"We often say we are like a married a couple trying to get a divorce, but we always meet up again," Iceland coach Heimir Hallgrimsson said.

"We know Croatia. We know what kind of game it is going to be."

Australian Associated Press