The 33-year-old has been handed the armband by usual skipper
However, with Republic of Ireland having lost both of its opening games to
Duff said: "It's obviously an awfully proud moment, but I would take three points tomorrow ahead of 100 caps at the minute.
"I know how much it means to myself and my family and what have you, but I am not trying to make a big deal out of it.
"I just want to get on with the game and hopefully do the business."
Duff has never been one of the more talkative members of the squad and his appearance on the stage alongside Keane and manager Giovanni Trapattoni at the pre-match press conference in Poznan was something of a rarity.
He joked: "I was dragged here kicking and screaming, to be fair. I'm never one to make big a thing out of anything in life.
"It's something that I will probably look back on maybe next week, maybe next year.
"It's a feat, but at the minute, I just want to get a good performance and a good result tomorrow."
Keane had no qualms over passing on his duties for the night to a man he holds in the highest esteem both on and off the pitch.
The striker said: "He's been obviously a massive, massive player since he made his debut. We made ours together and we have been through a hell of a lot together.
"As we all know, he's a top, top-class player and the respect that he has around the dressing room from every player and how people speak so highly of him.
"When you are around him, he is great company and not only that, he's a top, top player.
"We have been very good friends since we made our debuts and it was only right for me to make this gesture because he has been an absolute credit to his country and will go down as probably one of the best players that we have ever produced."
Duff is one of a series of 30-somethings in Trapattoni's squad who has been tipped to call it a day after the finals.
The Fulham midfielder admitted he had made his decision in his own mind, but was not about to go public as he contemplated playing on into his mid-30s.
It remains to be seen whether that plan involves club and country, however.
Duff said: "I think I have made my mind up what I'm going to do, but it's probably not the right time to be letting anyone know.
"I am sure the rest of the lads know what they are going to do as well
"With regards to playing on well into my 30s, I don't think it should be a problem. I look after myself and feel as good as ever at the minute, so I don't see why not."
Duff, who made his senior debut alongside Keane against the
However, it is the disappointments which stick in his memory, and in particular, the FIFA World Cup play-off defeat in
He said: "I always seem to remember the lows rather than the highs, for some reason.
"It was obviously nice getting to the World Cup and stuff like that, your debut, your first goal - the first goal took a while.
"Then I suppose the lows, obviously the
The post mortem on Republic of Ireland
Duff said: "What went wrong in this tournament? I don't know, I suppose you can just say we weren't good enough when it came to the crunch.
"They are two very disappointing results and we are looking to restore a bit of pride tomorrow."
UEFA president Michel Platini said preparations for Euro 2016 were "progressing well" after a meeting of the organising committee in Lille.