Heimir Hallgrimsson knows his future as the Republic of Ireland's head coach will come under scrutiny after a stunning 2-1 loss in Armenia dented their World Cup qualification hopes.

Ireland are bottom of Group F with one point from their first two games, having followed up a 2-2 home draw with Hungary with a humiliating loss in Yerevan.

Eduard Spertsyan opened the scoring from the penalty spot following a Nathan Collins foul in first-half stoppage time, then Grant-Leon Ranos tucked home to double Armenia's lead early in the second half.

Roma loanee Evan Ferguson quickly pulled one back to become the first Ireland player to net in three competitive matches in a row since Stephen Ireland in 2006-07. 

But unlike against Hungary on Saturday, Ireland were unable to complete the comeback as their hopes of reaching next year's tournament took a monumental blow. 

Hallgrimsson told RTE: "Today I take the blame for this. But the players are the same players we were happy with in the second half against Hungary.

"So, as I said, it is an off day, and we have to look inside and see what we can do differently."

Hallgrimsson, who took the reins last July, has won four of his 12 matches at the helm, drawing three and losing five.

He knows that if Ireland fail to qualify for a fifth successive major tournament, he may pay with his job.

"The job of the coach, if they are not producing, then of course it is always a question," he said.

"I am not naive, it is understandable now, after this performance. I will take the blame, the players need support, and we need to encourage them."

Ireland visit Portugal for their next World Cup qualifier on October 11, ahead of a rematch with Armenia in Dublin three days later.