Wes Hoolahan has been ruled out of the Republic of Ireland's World Cup qualifier against Wales with a thigh injury.

The Norwich man is set to miss a number of weeks as a major selection headache threatens to disrupt manager Martin O'Neill's plans for the game on Friday.

"He'll be out, Wes is out, definitely out," said O'Neill. "We got the news through on the scan this morning and obviously it's not great, not great for us, not great for him and not great for his club.

"He's going to be out for quite a number of weeks, I believe."

With star man Robbie Brady already suspended for Friday night's showdown at the Aviva Stadium, O'Neill has seen first-choice central defensive pairing Shane Duffy and Ciaran Clark, as well as midfielder Harry Arter, succumb to injury.

And as the Ireland squad trained for the first time this week in Abbotstown today, he was keeping his fingers crossed over a series of other concerns.

"How long have you got?" - Martin O'Neill discusses the longest injury list he can remember in his time as Ireland manager. #rtesoccer pic.twitter.com/eJe9y0GkN4 — RTÉ Soccer (@RTEsoccer) March 20, 2017

Asked for an injury update, a frustrated O'Neill said: "How long have you got? It's the lengthiest list of injuries that I have known since I have come into the job, and unfortunately it's happened at a really crucial time for us.

"However, other players will have to step up and just be ready for Friday. Do you know, I have often said this before, that you just curse your luck and get on with it.

"The irony of all of this here is that way back when Gareth Bale got injured in November-time, everybody was talking about Wales possibly having one of their major players out of the team, and it turns out that we are the ones who are doing the suffering.

"But it is what it is and we'll get on with it and we'll be ready to go on Friday."

Seamus Coleman and Jonathan Hayes were both nursing ankle problems, but are expected to be fit, although news of Daryl Murphy (calf) was not so encouraging.

Newcastle striker Murphy was due to have a scan on a calf problem in Dublin.

Everton midfielder James McCarthy, who has missed his club's last two games with a hamstring injury, was due to meet up with the squad later on Monday, as was Colorado Rapids striker Kevin Doyle.

O'Neill added: "James has come over and we'll see how he is. He'll just take it on a day-to-day basis. He thinks that he might be able to make it - that would be great if he can. If he doesn't, well, we'll just have to do without him.

"Seamus has picked up a knock - it's precautionary. If he doesn't train tomorrow, he'll train on Wednesday, so he'll be okay. You know what he's like.

"Daryl, speaking to him last night, he is giving himself a chance. He's certainly not ruling himself out at this moment. We'll see what develops with the scan."

Unbeaten Ireland currently top Group D with 10 points from their opening four qualifiers with the Welsh four points behind in third place.