Manchester United legend Roy Keane admitted that he seriously considered retiring after an infamous bust-up with Newcastle hero Alan Shearer in September 2001.

The Premier League icons, who were captaining their respective teams at St James’ Park that afternoon, clashed in the closing stages of the match.

Keane went to take a throw-in before being pushed by Shearer, whose side were leading 4-3. The Irish midfielder reacted by throwing the ball at Newcastle’s star striker.

The pair then exchanged words before Keane swung a punch at Shearer, who dodged it.

Referee Steve Bennett was right next to the incident and was left with no choice but to send Man Utd's skipper off.

Roy Keane sent off v Newcastle in 2001

15 Sep 2001: Man Utd Captain Roy Keane is shown the red card during the FA Barclaycard Premiership match between Newcastle United and Manchester United played at St. James Park in Newcastle, England. Newcastle won the match 4 - 3. \ Mandatory Credit: Gary M Prior /Allsport

Keane regretted not punching Shearer

Keane, in typical Keane fashion, admitted that his big regret was not punching Shearer.

More surprisingly was the fact that Keane genuinely considered quitting the sport following the incident aged just 30.

“I lost my temper, we were losing 4-3, I think, in the last minute,” Keane said.

“If you’re going to get sent off, the worst thing is, I pushed him. If you’re going to get sent off you might as well punch him properly because you’re going to get the same punishment.

“You might as well be hung for a sheep as a lamb. That’s what I was thinking afterwards. It was just a push. It was ridiculous.”

Roy Keane v Alan Shearer

15 Sep 2001: Man Utd Captain Roy Keane takes a swing at Newcastle captain Alan Shearer during the FA Barclaycard Premiership match between Newcastle United and Manchester United played at St. James Park in Newcastle, England. Newcastle won the match 4- 3. \ Mandatory Credit: Gary M Prior /Allsport

Keane: I told Ferguson 'I've had enough'

He added: “I was fed up and annoyed with myself. Especially after the match. The gaffer [Sir Alex Ferguson] never really had a go at me. I knew from his body language – ‘how much more, Roy?’

“I saw him the next day and I said ‘I’ve had enough’ – and I meant it.

“I came back that night and didn’t sleep a wink. I spoke to Theresa [his wife] when I got back and she said ‘You’re mad’. I said ‘I know that’.

“The next morning I went to see the gaffer he said ‘you’ll miss it’ and I was convinced I wouldn’t but I suppose deep, deep, very deep down of course I knew I would miss walking out at Old Trafford.

“I loved playing at Old Trafford and I loved playing for United.”

Video: Roy Keane vs Alan Shearer in 2001

Watch the video here:

What happened in the tunnel between Keane and Shearer?

Speaking 16 years after the incident in 2017, Shearer revealed that Keane was waiting for him in the tunnel.

“It was funny because when he walked off the pitch, it was only the last minute or two of the game,” Shearer said on The True Geordie Podcast.

“He’d been given the red card and he was waiting for me at the top of the tunnel at St James’, we tried to get to each other but we couldn’t.

“It was like ‘hold me back, don’t hold me back’, but we couldn’t get to each other. It would have been interesting.”

Roy Keane vs Alan Shearer

15 Sep 2001: Man United Captain Roy Keane squares up to an impassive Alan Shearer during the FA Barclaycard Premiership match between Newcastle United and Manchester United played at St. James Park in Newcastle, England. Newcastle won the match 4 - 3.\ Mandatory Credit: Gary M Prior /Allsport

When True Geordie said he thought Shearer would have knocked Keane out, the Premier League’s all-time leading scorer replied: “Of course I would have”.

Now that’s an exhibition boxing match we’d all love to see.