The Brighton centre-half, who has 17 caps and two goals for his country, has won praise for his consistent performances at club level this season, helping a newly-promoted side to 11th place in the Premier League and to within 90 minutes of a Wembley semi-final.
His partnership with Englishman Lewis Dunk, a similarly-sized and equally combative defender, has been the basis of that success — Albion have conceded fewer goals than sixth-placed Arsenal who they beat 2-1 recently — and brought him to the attention of BBC correspondent Garth Crooks.
The Tottenham legend described Duffy and Dunk as having played "like two bouncers with strict instructions not to let anyone into the nightclub" following that victory over Arsene Wenger’s side at the Amex in which the Seagulls were outstanding.
On face value it wasn’t the most gushing of plaudits; there’s far more to Duffy in terms of technique, positioning and aerial ability than just brawn and muscle – you don’t survive and thrive in the Premier League on those qualities alone. But on a day when he’s about to come up against United powerhouse Romelu Lukaku, perhaps it is rather timely...
“Yeah, I saw that description — and I’m not going to complain,” Duffy said. "I’m happy to take it when you get compliments like that. We know we’ll have to be the same at Old Trafford because they have a big strong team, particularly with Lukaku up front. Hopefully we can go up there and remind them early on they are going to be in a game. We’ll certainly be ready for the battle.”
Brighton go into the tie as huge underdogs, even though United are on a low after losing to Sevilla in the Champions League in midweek, but head to Manchester with memories of a narrow and creditable 1-0 league defeat there this season to hold onto.
Manager Chris Hughton, a Republic legend himself, had described it as his team’s best performance of the season — until they stepped up a gear against Arsenal.
“It’s true that we played very well when we went there in the league and we felt unlucky not to get something from it,” said Duffy. “But to be honest that doesn’t mean anything because we lost the game, so it didn’t count for anything.
“Every game is different and we are a different team now, too. We’ve brought in players in the transfer market who have done well and we’ve got players on form. You know it is going to be difficult at Old Trafford but we are one game from Wembley and it’s the FA Cup so we’ll give it everything.”
The game is a repeat of the 1983 FA Cup Final when Brighton famously held United to a 2-2 draw before losing the replay 4-0. There was a strong Irish connection that day too — Brighton’s squad included captain Tony Grealish and striker Michael Robinson as well as Gary Howlett and Gerry Ryan, while United boasted the likes of Frank Stapleton, Kevin Moran and Ashley Grimes.
“You can’t play at this club and not know about that game,” admitted Duffy. “I watched the FA Cup when I was young and you know that Manchester United have a big history in the competition. They have had some great Irish players but I’m not going to get into who I watched or who I wanted to win. This is just about Brighton and getting to Wembley.
“Staying in the Premier League is the priority for this club but we know what the FA Cup means to the club and to the fans, it has such a great history.”
Duffy, 26, will join up with the Republic squad following the quarter-final tie, for a friendly international in Turkey he sees as vital in the team’s development.
“We’ll go to Turkey looking for a good result to set us up for the future," he said. “Recovering from the World Cup disappointment wasn’t easy, for the team or for me personally. It still hurts. But you can’t let it affect your season, you have to get straight back in there. I think I’ve done that and I’m happy with how I’ve performed since then.
“Going to Old Trafford is a big test for me and for Brighton; but if we can stay in this division and get to Wembley then it can only help with my international future.”
Duffy hopes to be joined by captain Seamus Coleman in the Republic defence for the first time since the Everton man suffered a broken leg in a qualifier against Wales a year ago.
“It’s going to be a huge lift for everyone having Seamus back in the squad, just what you need after the disappointment we went through,” the centre-back said.
“We missed him a lot in qualification, any team would, so to have him back means a lot to us all. He is such a top quality player. It’s a new start for us now and I hope I can take my club form into the international games.”