Flying Eagles coach John Obuh has declared that Friday's opening World Cup match against Portugal is a must-win one. The Nigeria U20s will take on their Portuguese counterparts from 7pm Nigerian time at the Kayseri Kadir Has Stadium to kick start their 2013 World Cup campaign. 'This is our first game at the World Cup. It's very crucial and a must-win match because a win will ease the pressure on the team and it will boost our confidence,' said Obuh, who is making his second appearance at the U20 World Cup. 'Victory on Friday against what many regard as a good team from Portugal will give us qualification to the next round of the competition.' Two weeks ago at the Toulon International Tournament in France, Portugal edged past Nigeria 2-1. Incidentally, both teams also battled leading up to the 2011 World Cup in Colombia. The first friendly in Lisbon ended goalless, while Portugal won the second match 2-0 in an invitational tournament in Panama. Portugal will go on to reach the World Cup final, while Nigeria crashed out at the quarter finals. Obuh said the Flying Eagles must therefore ensure they make fewer mistakes on Friday. 'We have to be calm and make sure we make fewer mistakes against a good side like Portugal. Mistakes have often cost us dearly and so we cannot afford such,' he warned. 'And we also have to take our chances in front of goal while always making sure we keep a clean sheet at all times.' The Flying Eagles, who have already trained with the official match balls Cafusa, will have a first feel of the match venue Thursday evening. Click here to read full news..