The team meet France in the Second Round on Sunday afternoon at 2pm
Republic of Ireland manager Martin O'Neill has hailed "a remarkable performance" from the player after the team's 1-0 win over Italy.
The Derry native spoke on Thursday morning to the Pat Kenny Show and paid tribute to the fans, hailing the "extraordinary scenes" after the game.
"The players were absolutely ready for the game last night, really ready for it", O'Neill told Pat Kenny. "This was relentless pressure. When we had the ball we played... It wasn't just ferocious effort which we obviously needed but it was the ability to get it down and play and surpass the Italians."
Before the game, O'Neill made four changes to the side that lost 3-0 to Belgium at the weekend. He gave his reasons for those changes citing fatigue as an issue. "Outside (Ciaran) Clark, three of the players are in their 30's. Those players who played in the Belgium game, played splendidly against Sweden. It's a squad game... We have a squad of players and I believed we needed to be re-energised."
Despite the changes to the team, the manager claimed that the mood in the camp had not altered and changes may be made again ahead of the France game. "Everybody wanted to see the team do well, including the players who were left out. Who knows? They may roar back again."
The stadium in Lille had it's roof closed, which O'Neill thinks helped the team. "(The roof) added to the atmosphere. It was a bit hot and sticky, but great nevertheless. I think the noise levels coming from our fans was extraordinary... When it's enclosed, it's even more deafening."
With four points, Ireland were the second-best third-placed team to advance. The confidence of beating Italy, will continue into the game with hosts France. "We had our work cut out in the group. For us to get four points in the toughest group must give you some confidence."
Sunday's game is Ireland's first against France since the infamous 2010 World Cup Play-Off in 2009 when Thierry Henry handled the ball in the box. O'Neill says it wont be the only motivating factor for the players. "We have all the motivation in the world regardless of that. We have a side that love playing for their country... Its a driving force among this group of players."
He hopes the green army will be in force in Lyon on Sunday, and can match the impact made on Wednesday night. "Fans and players alike almost fed off each other. The energy between both sets was gigantic and it was enough to cross us over the line."