Duffy said: "On another night, we could have got one and it's disappointing to take. It wasn't for the lack of effort, as always, from us.

"But I'm trying to stay positive. We're still in it, we're not out and we've got to do it the hard way, like we always do."

Mick McCarthy's side produced their most compelling performance of the campaign to set the stage for a first competitive victory over the Danes since 1979, but in the end they were undone by their inability to convert pressure into meaningful chances.

Matt Doherty's 85th-minute equaliser, which cancelled out Martin Braithwaite's earlier strike against the run of play, was only their seventh goal in eight qualifying games and an eighth proved beyond them in a frenetic finish at the Aviva Stadium.

However, Duffy is convinced that more of the same will serve the Republic well when they reconvene in March.

He said: "It's difficult, but that's football. If you make mistakes at the highest level you get punished and that's sort of what happened to us tonight.

"We try to play like that every game, to be honest, but it's easier said than done. We've just got to keep everyone fit until March and playing well at club level.

"But that's the benchmark, we have got to stay at that level now, energy, even passing the ball, playing, if it's not on, we come back out, the simple basics which we've worked on.

"I thought we pressed them quite well and they didn't get their game going, really, and that's the benchmark.

"Whoever we get in March, we've got to do that again."

Duffy was handed the armband in the absence of suspended skipper Seamus Coleman, although he admits he would readily have swapped his immense pride at leading his country out for the win which would have taken them to a third successive European Championship.

He said: "I tried not to think about it, to be honest. My family were very proud and stuff like that. I'd swap it all for a win, but it was obviously a special night.

"It doesn't feel special at the minute because we didn't get through, but it's something I'll always be proud to say to my kids when they grow up."