VIDEO: Martin O'Neill joins Roy Keane in cringe club! Celtic boss forced to apologise after embarrassing gaffe at press conference

O'Neill quickly realised what was happening and took his phone out to cancel the call. The moment itself interrupted a journalist who was asking a question ahead of Sunday's league game against rivals Rangers at Ibrox.

And after quickly cancelling the phone call, O'Neill turned to the reporter in question and said: "I really do apologise, that is bad manners. I'm sorry."

The moment caught the Bhoys boss off guard, who turned then said: "Do you want to ask me the question?"

The moment was similar to a recent Roy Keane gaffe, where his phone went off during an episode of The Overlap, which left Wayne Rooney, Gary Neville and Jamie Carragher in stitches after the call interrupted Ashley Cole.

"The ill-discipline!" exclaimed Neville, before Carragher was desperate to know who was calling the uncompromising Keane.

The former Manchester United midfielder was raging at the error, saying as much afterwards. "My phone is always off," said Keane by way of apology. "I'm raging with that. My phone is always on silent."

Rooney then added: "And he [Cole] was just saying them older players are so important to learn from!"

Neville then went on to remind Keane about a similar incident that happened during the Irishman's time as Ipswich boss. The former defender wanted to find out who the culprit was, and Keane revealed he didn't find out until much later who had given a reporter in the press conference a buzz.

"I done an Ipswich game last year for Sky," he explained. "The guy whose phone was ringing came over and apologised. A reporter came looking for me and I asked him. I said, 'well why didn't you switch it off? All them years ago?' He said 'I was nervous. I didn't know what to do'. But he apologised for that and I apologise for that."

O'Neill, meanwhile, will hope Celtic can build upon Thursday's 1-0 win at VfB Stuttgart to boost their title hopes. Celtic sit six points behind league leaders Hearts following last weekend's 2-1 defeat to Hibs, though do have a game in hand on the Jam Tarts.

And O'Neill was full of praise for his players following their narrow victory over the German side, despite crashing out of the Europa League 4-1 on aggregate. "I’ve been delighted with the team, absolutely delighted with the side. The fourth goal really deflated us last week, but if we could contest tonight and maybe get an early goal, or at least not concede early on," O'Neill said.

"What do we do? Well Luke scored a great goal for us within a minute or two of the game and then we’ve got something to go for. Of course, we were going to be under pressure at times in the match, they’re playing at home, they’re a very good side, my view is that they are very capable of winning this competition, they may or may not do that, but they are very capable of winning it.

"But the players showed great determination. At times we played some really nice football as well. "Overall, it was a brilliant effort, the lads got very tired before the end and we just couldn’t get the ball often enough to press, but overall I couldn’t’ be more pleased.

"Heart and desire is something that, in the scheme of things, is still important. Now heart and desire will not win you every single football match, you’ve got to be able to have the ability to get it down, play under pressure, all those things, but it does help when the going gets tough."