Evan Ferguson’s fourth goal in five competitive internationals kept the Republic of Ireland’s World Cup dream alive as they edged past 10-man Armenia to claim their first Group F victory.

Head coach Heimir Hallgrimsson had admitted in advance that he would accept a “s****y” performance and a 1-0 win on a night when victory was the only option, and Ireland eventually delivered – if only just – as they made the most of Tigran Barseghyan’s senseless second-half dismissal for a headbutt on Finn Azaz.

Twenty-year-old Ferguson, who had passed up a glorious opportunity to open the scoring seconds earlier, dispatched a 70th-minute header to seal a 1-0 win at the Aviva Stadium and ensure leaders Portugal’s visit to Dublin next month and the trip to Hungary which follows it are meaningful, if daunting.

They will need to be markedly better in both games than they were against a side ranked 103rd by FIFA if they are to stand any chance of claiming the runners-up spot after a performance which for long periods lacked the inspiration necessary to make life much easier than it ultimately was.

A promising start by the hosts soon evaporated as Armenia settled, although they were unable to penetrate Hallgrimsson’s 5-4-1 out-of-possession shape, despite the probing of dangerman Eduard Spertsyan.

Ryan Manning, who was causing problems down the left, drilled wide at the other end four minutes later after Festy Ebosele had surged past defender Styopa Mkrtchyan on the opposite flank.

But Ireland enjoyed a major escape seven minutes before the break when a bandaged Barseghyan – he had earlier clashed heads with Dara O’Shea – played Kamo Hovhannisyan into space down the right and he crossed to the back post for Spertsyan to volley wastefully wide.

The first half drew to a close with neither keeper having to make a save of note and that was a significantly bigger problem for the home side, who left the pitch to a less than appreciative send-off.

It took a barge by Seamus Coleman – for which he was booked – on keeper Henri Avagyan as he collected a looping Azaz header to get the home crowd going and the temperature rose when Barseghyan thrust his head into the Southampton man’s face and was sent off seven minutes after the restart.

Avagyan managed to claw away Nathan Collins’ header from a Manning cross seconds later and then made a stunning save from O’Shea’s deflected header as Ireland sensed their opportunity, but a lack of precision continued to let them down.

Jayson Molumby fired high and wide on the turn from Manning’s pull-back and Ferguson shot straight at Avagyan after Azaz had turned smartly and slid him in.

But the Roma striker made amends with 20 minutes remaining when, after Ireland had worked a short corner, he timed his run to perfection to meet Will Smallbone’s cross with an unstoppable close-range header.

Avagyan made a remarkable stop to keep out substitute Adam Idah’s mis-hit attempt from point-blank range and the Swansea frontman saw an 89th-minute strike ruled out for offside as Ireland saw out a first home win in a World Cup qualifier since October 2017.