Following their 3-0 defeat to Belgium on Saturday, the Boys in Green must win if they are to have a chance of progressing to the knock-out stage and Keane emphasised the need for "bravery".
"Courage is a big part of being a footballer - and courage doesn't mean booting somebody, it's wanting the ball when sometimes you don't actually want the ball, if that makes sense," the Ireland assistant manager told reporters.
"Bravery, courage, and we need to see that in the next few days."
Having endured a heavy loss against Marc Wilmots' side in a game which saw a preponderance of individual errors, Keane also stressed that players must "make sacrifices" for the good of the team.
"You have got to be streetwise in this game," noted the former Manchester United captain.
"We’re not here to make friends, the fans are doing that. But from the players’ point of view, if you smell danger, if you can hold the player up and you can win the ball, fantastic, but if you think ‘we’re in trouble here’, then you do whatever you can to get the right result, and if that’s fouling, then you foul.
"It’s not a crime, you might get a yellow card, you might even get a red, but your team might win.
"Sacrifices, you’ve got to make sacrifices for your team. Does that answer your question? What do you think I would do?"
Ireland take on Italy in Lille on Wednesday, June 22.