Roy Keane and Alan Shearer both enjoyed hugely successful careers. The former captained Manchester United and won 17 trophies during his time at Old Trafford, while the latter, who also captained his side, is still the all-time Premier League top goalscorer and famously won the top-flight title with Blackburn Rovers in 1995.
The pair followed a similar path after the conclusion of their playing days, which included stints as managers - albeit only as a caretaker in Shearer's case - and more recently, in punditry. Keane is currently one of Sky Sports' most popular and explosive pundits, with the Irishman also occasionally working for ITV Football. Shearer, meanwhile, is one of the BBC's biggest names.
Given that United were considerably more successful than Blackburn Rovers, and later Newcastle United, the rivalry that began to develop between Keane and Shearer came as somewhat of a surprise to many people. Two of the league's most prominent figures had somehow become on-field enemies.
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The spark that ignited the feud occurred in 2001. The pair famously clashed on the pitch in the dying seconds of the Magpies' 4-3 home victory against United, with Keane petulantly throwing the ball at Shearer's head after the Magpies striker blocked a quick throw-in. The Irishman would go on to shove his opponent, before slapping the yellow card that was waiting for him out of the hands of referee Steve Bennett.
Keane was jeered by the St James' Park crowd - who had applauded his subsequent red card - with Gary Neville and David Beckham having to pull his teammate away from Shearer.
Shearer, having stared back into Keane's eyes, certainly played his part in the incident. It was, in some ways, just as villainous as the acts performed by his foe, but the difference was that he managed to keep his cool. The United midfielder was frustrated that the Magpies ace, who had put Newcastle ahead in the seven-goal thriller just eights minutes prior, did not fall into his trap.
The drama, albeit a blow for United, was entertaining for spectators, and it was far from over, too. An incensed Keane was waiting for Shearer in the tunnel after the match - an incident that the BBC pundit recalled last year. He told The Athletic: "When the final whistle went, Roy was standing at the top of the stairs waiting for me.
"I'm pretty sure a few more choice words were exchanged, there was some bustling and scrambling, but there were way too many people between us for anything physical to actually happen. That's usually how it pans out in football."
When asked why he decided to push Shearer, Keane previously said: "I lost my temper, we were losing 4-3, I think, in the last minute. 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."
The former England striker has been keen to insist that he didn't view the Reds midfielder as an "enemy" - but Keane, on the other hand, has certainly never been complimentary when it comes to talking about Shearer. While the pair currently work for rival broadcasters, there was a time when they were both doing punditry work for the BBC.
During an episode of The Overlap Live, Keane was asked if any of the feuds he was involved in on the pitch had led to issues in the TV studio. He appeared to indicate that him and Shearer were still not on good terms.
"Yeah, most weeks!" Keane replied. "There's one or two I've done games with where we couldn't get over that hurdle of what happened in the past."
When he was pushed to reveal the player's name, he said: "Shearer... forget it."
Although Shearer had suggested that any lingering problems between himself and Keane were non-existent, he appeared to reignite the feud earlier this year. The 52-year-old seemingly changed his story about the clash, claiming, or potentially joking, that Keane had actually ran away from him.
The former Newcastle man, who had previously suggested that Keane's "bark is worse than his bite", spoke about the incident ahead of the FA Cup final in May.
"Roy didn't like me for some reason, I don't know why. He was getting beaten that day, that's [probably] why," said Shearer. "We were winning the game and there was only a minute left. I was waiting for him in the tunnel - he ran away!"
However, Shearer's former teammate Craig Bellamy didn’t quite recall it that way. In fact, he suggested that the Magpies striker was, conveniently, taking his time to exit the field following the full-time whistle.
He claimed in his autobiography: "I saw him waiting for Alan in the tunnel at the end of the game and Alan didn’t seem to be hurrying off the pitch! He was one of the last to come off actually, which we all made sure we remarked on when he finally made it back to the dressing room. Keane had to be dragged into the United dressing room by then."
Keane, meanwhile, almost considered retirement after being sent off in the Premier League clash with Newcastle. The Irishman, known for his professionalism and determination to succeed and win, was so annoyed by his actions that he thought about walking away from the game - despite only turning 30 the previous month.
"I was fed up and annoyed with myself. Especially after the match," Keane explained. "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.
"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."
The Irishman, thankfully, decided to continue playing. He would eventually leave Old Trafford having played 473 matches for the Reds, registering 51 goals and 36 assists. Keane retired as a Premier League legend. As did Shearer.
While the pair were quick to clash on the pitch - and are unlikely to ever be friends off of it - they clearly had respect for each other. That, unlike Keane's attempted swing, was never missing.
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