The Eagles are to battle Iran on June 16 at 8 p.m. in Curitiba.
Allen told the News Agency of Nigeria (NAN) in Lagos that the team should play the match with the right attitude, to ensure victory for Nigeria.
“The entire nation is expecting nothing less than victory against Iran and we can only achieve victory if our players are not just physically fit but are also psychologically ready for the match.
“With the right attitude and mentality, nothing will stop the team from getting the three points at stake in the encounter.’’
The coach noted that a win in the opening match was crucial for Nigeria’s qualification for the next round of the tournament.
Allen, however, cautioned the Joseph Yobo-captained side against underrating their opponents.
“If we can get the full points from this match, there is the possibility that we will get to the round of 16 in Brazil.
“No team is a pushover when it comes to the World Cup and this is also applicable to the Iranians.
“So, the Super Eagles should play the match with all seriousness,’’ Allen advised.
NAN reports that Nigeria are in group F alongside Argentina, Bosnia-Herzegovina and Iran.
The competition which began on June 12 is to end on July 13. (NAN)