Republic of Ireland captain Seamus Coleman hae sustained a broken leg after a tackle from Neil Taylor in the stalemate against Wales.
The Everton defender was in real distress as physios attempted to hold his right leg in place, as he was stretchered off in the 68th minute.
Neil Taylor was shown a straight red for the tackle and O’Neill,Ireland boss held his head as Coleman was given oxygen as he was taken to the hospital.
“Apparently it wasn’t the best challenge in the world – I haven’t seen it back – but naturally disappointed. He’s gone to hospital and I think it’s broken.
“I saw Seamus’ reaction – he was holding his leg up and it didn’t look good.”
Wales boss Chris Coleman said: “First and foremost I think the most important thing is Seamus Coleman. We’re told that it’s not so good, which we are sorry for.
“Neil Taylor is not really that type of player but, if he’s got it wrong… I’ve not seen it again. He’s in the dressing room and he’s quiet and despondent.
“It’s a tough one for Seamus. Thoughts are with him first and foremost. We hope and pray it’s not such a bad one.”
Wales’ Gareth Bale said: “We never wish that on any fellow professional. Obviously we don’t know how bad it is but we wish him a speedy recovery.”