Martin O'Neill reveals Celtic change that saved dream and when Alex Oxlade-Chamberlain could make debut

But substitute Junior Adamu, signed last week on loan from German side FC Freiburg, had, if not the last say, then the most significant one with an equaliser six minutes into time added on. It proved the last kick - or indeed backheel flick - of this extended period.

Midfielder and man of the match Ethan Hamilton had given Dundee the lead with a brilliant strike from just outside the box four minutes after half time.

Sebastian Tounekti scored what proved the winner two minutes into extra time to send Celtic into the last eight. Dundee’s hopes of winning at Parkhead in the Scottish Cup for the first time—and their first win there at all since 2001—were brutally extinguished.

“Naturally I am delighted to be in the hat for the next round,” said O’Neill afterwards. “That seemed a long, long way away in what was it, the 97th minute? But we showed determination to go to the very end and try to create something. So pleased for the team, naturally. I thought they were brilliant, really brilliant, to see that through despite the mistakes we made during the course of the game.”

O’Neill conceded he had accepted the Scottish Cup would have to be written off as the seconds ticked by. He couldn't even console himself with thoughts of next year as he's only agreed to stay until the end of this season.

“It is easy for managers to say ‘I always felt (a chance was coming),” he said. “When the ball is in the penalty area, you might think something is going to materialise. I thought his (Adamu’s) introduction was probably key, as much as anything else. If Dundee had managed to kick the ball clear, then that’s probably the game over. But we found a way to save the game and we found a way to win it. “

Adamu replaced Tomas Cvancara with 11 minutes left. “Naturally I am delighted for him and he will be delighted for himself," said the manager. "He wants to do well, as they all do. But he in particular was delighted to come and be a part of proceedings. I am really pleased for him.”

O’Neill has his say on swathes of empty Celtic Park seats

When the ice-cold nature of the finish was pointed out to him, O’Neill smiled: “It did not feel ice-cold myself. But the relief of getting the goal and the momentum carrying on to the start of extra time.”

The goal roused the Celtic supporters, for perhaps the first time in a match. There were large areas of empty seats, partly due to a boycott called for by the Celtic Collective group and partly because of this being a 5.30pm kick-off live on television and which wasn’t on the season ticket book.

O’Neill said he understood the frustration of the fans as Celtic toiled to break down a well-organised Dundee team. “I think it’s the nature of it,” he said, when asked about the flat atmosphere among the fans and the success or otherwise of the boycott. “It’s expensive to travel. You are talking about a 5.30pm kick off on a Saturday evening and if you’re travelling from Ireland, then they would find that difficult. I was pleased with the crowd and pleased with the number who turned up and naturally I am delighted be in the hat.”

New signing Alex Oxlade-Chamberlain was introduced to those fans present before kick-off. Confirmation of his arrival on an initial six-month contract came too late for him to take part though O’Neill seemed confident he would be involved soon. Celtic host Livingston on Wednesday night.

He had been training with former club Arsenal in recent weeks. “We will know in a couple of days (how he is fitness-wise),” he said. “He looks in really decent shape, he is not carrying any weight and things like that. He is raring to go.”

For Dundee, it was a case tale of Scottish Cup heartbreak although Pressley stressed how proud he was of the players. He added that he had no complaints about the time keeping. Adamu’s equaliser was scored with the clock having ticked into the sixth minute of injury time after five extra minutes had been signalled.

“I have no complaints. None at all,” he said. “We keep playing until the referee blows his whistle. Of course, we're disappointed.

“Of course, if the official puts up five minutes and it leads to 96-and-a-half ... but we have to endure that. We have to stay focused. I'm just disappointed because I think our players deserved the win.

“It’s gut-wrenching,” he added. “I’m exceptionally proud of the team. To a man, they were exceptional. They left nothing out there. But not only did they show incredible effort, I thought they showed a lot of bravery. Bravery to take the ball under pressure and play and build. So there were so many good things and the truth is, I thought we were there. You always have to give clubs like Celtic a great deal of respect. They never give up. I just thought we were there...”