Northern Ireland manager Michael O'Neill has insisted that his team are capable of picking up a surprise result in Portugal on Tuesday.
O'Neill's side are heavy underdogs for the World Cup qualifier in a match that will mark Cristiano Ronaldo's 100th international appearance.
He told the Belfast Telegraph that Northern Ireland have formulated a gameplan to frustrate a star-studded Portuguese attack in Porto.
O'Neill said: "The best hope for us is that the work we have put in is put into practice in the game.
"We have to recognise the quality of the opposition but we are not sitting here just hoping for Ronaldo to have an off night, we have trained to this level in preparation.
"It is our job to make sure they do have an off night and we can add to them having a frustrating night by taking our opportunity when it presents itself."
The Irish travel to Portugal without a number of key players, including Chris Brunt, Shane Ferguson and Gareth McAuley.
