Chris Coleman urged Wales to learn lessons from the Euro 2016 defeat to England and control their emotions during the last-16 clash against Northern Ireland.
The Parc des Princes will host the all-British knockout tie on Saturday after Wales progressed as Group B winners and Northern Ireland's 2-0 victory over Ukraine alongside slender losses to Poland and Germany made them the fourth-best third-place finishers.
Wales' only setback during the round-robin phase came as Daniel Sturridge struck a last-minute winner to seal a 2-1 triumph for England in Lens - the upshot of a match where Coleman felt Wales' battling qualities outstripped their work in possession.
"What we did in our last experience playing a team from Great Britain was we fought really well, we'd fight all day long," he told a pre-match news conference.
"We stood our corner out of possession but when we had the ball we never played anywhere near our capabilities because we got caught up in the game, with the emotion of it because it's a derby game.
"Tomorrow, the 90 minutes don't last forever. It comes and it goes. It's up to us how we want to enjoy that experience, how we want to go into the game and what we want to do once the game starts.
"We have to take the emotion out of it. Don't get me wrong, you need a bit of emotion, but if you get too emotional then your game plan is out of the window.
"The game is Northern Ireland, it could have been Turkey. All they are to us is the opposition and they are playing in different coloured jerseys.
"Where they are from is irrelevant. We must follow the game plan and do what we're good at.
"We need to try as much as we can to take that emotional side out of it."
Coleman's men find themselves in the kinder side of the draw, with champions Spain, hosts France, Germany, England and Italy among those set for a titanic tussle in the bottom half.
Nevertheless, the Wales boss believes it would be fatal to his team's prospects if they were to start mapping out a route to the final.
"Such is the quality of the company that we're in at this tournament, if we every dared to think the next game was a stepping stone to something it would be all gone and we would be in the plane home," he added.
"Not a team in this tournament can think like that - not Spain, not Germany.
"Russia was great, we won 3-0 and the performance was mouth-watering, but the two games before hand were touch and go. Nine times out of 10 the games are very close, such is the quality of the teams here.
"We can't look past the next game or the next 45 minutes. I wouldn't dare to do that, the players wouldn't. We certainly don't talk about a route to the final.
"There is not a team at this tournament who should think like that. Football throws up a lot of surprises and it can bite you on the backside."