Plenty of people who came up against Roy Keane during his playing career will agree he wasn't the kind of player you'd want to upset.
To call the Irishman confrontational would be an understatement, with his punditry style arguably just an extension of a playing career in which he wasn't afraid to let his words - or indeed his actions - do the talking.
From his tough tackling to the explosive MUTV rant which accelerated his Manchester United exit, he was always up for a war of words... or just a war, full stop.
That's not to say there weren't a few individuals prepared to stand up to the former United captain - both teammates and opponents - and what followed was often memorable.
Here, Mirror Football picks out five examples of players who gave Keane a taste of his own medicine.
What is your most memorable Roy Keane moment? Have your say in the comments section
Peter Schmeichel
There aren't many Manchester United players who had the seniority and respect to feel they might have been able to confront Keane, but Schmeichel certainly ticked those boxes.
However, there's a difference between ticking the boxes and escaping unscathed, as the Dane soon discovered.
"There was drink involved," Keane said of the altercation during a Man Utd pre-season tour in 1998, when he took issue with Schmeichel while the pair were at the team hotel.
"He said: 'I've had enough of you, It's time we sorted this out.' So I said 'Okay' and we had a fight. It felt like 10 minutes. There was a lot of noise - Peter's a big lad," Keane recalled in his autobiography.
"Peter had grabbed me, I'd head-butted him - we'd been fighting for ages," he said, before the pair later earned a dressing-down from Alex Ferguson for waking club legend Bobby Charlton.
Vinnie Jones
When it comes to 90s Premier League hard men, Jones is one of the few who can stand toe-to-toe with Keane both literally and figuratively.
Earlier this season, Keane spoke of United's lack of edge in the Manchester Derby, saying "I've often had it when I've not been at the races in a game and I go, 'You know what, what I might do is go and smash into somebody'."
Keane had plenty of experience of that from his playing days, both in terms of giving and receiving, and Jones certainly let the Irishman know he was there during an FA Cup clash in 1994.
United ended up winning the game, but Jones took aim at a number of United players - including a 22-year-old Keane - during his Wimbledon team's 3-0 defeat.
“To be honest Roy didn’t make a lot of noise when I played him – I don’t really remember a tackle," the Welsh international would later say, in a comment which showed he had an idea of how to push his opponent's buttons on and off the pitch.
"A fantastic footballer, yes, and a man I like and respect, but I’d have him well below Billy in the pecking order, and below Steve McMahon and Bryan Robson too.”
Alan Shearer
Reflecting on his interactions with Keane, former Newcastle striker Shearer claimed the midfielder's "bark was worse than his bite".
It's easy to say that from the safety of the pundit's chair, but Shearer also refused to back down when the opportunity presented itself on - or at least near - the pitch.
"Towards the end of Newcastle’s dramatic 4-3 victory over Manchester United and in a moment of frustration, Roy threw the ball at me, there was a delicate, polite conversation (OK, it wasn’t either of those things), he took a swing and missed and was then shown the red card," Shearer recalled in a column for 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 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."
The ex-striker said he and Keane have "always got on well," but it's sometimes those with the better relationships who can allow things to get heated. Certainly it can lead to a situation where no one is prepared to back down.
Gabriel Heinze
As Schmeichel had shown earlier, it wasn't just opponents who tested out whether Keane's bark really was worse than his bite.
Argentina defender Heinze was no shrinking violet himself, and the former Marseille man's time at Old Trafford only briefly overlapped with that of Keane.
However, there was still time for a coming-together, when the pair were the first two United players to return to the dressing room after the kind of defeat which leaves no one in a good mood.
"I didn’t want to speak to anyone as we lost," Heinze told Pura Quimica in 2017 (via The Star ).
"I didn’t understand English, just the bad words. I heard my name and 'f*** off' by Roy Keane, the best player.
"I knew that was bad so I stood up to him, this idol of Manchester, this great guy who everyone loved, and replied: ‘f*** off, you.' I don’t remember what happened next."
While Heinze's memory is a little hazy, it's probably telling that he doesn't have a second story of confronting Keane at United or anywhere else.
Patrick Vieira
For a while, the Premier League rivalry between Manchester United and Arsenal was also a rivalry between Keane and Vieira, with the pair encapsulating their respective teams.
The tunnel row between the pair was the most memorable coming-together, but Vieira attempted to give as good as he got on the pitch as well.
Back in the 1999-2000 season, the Frenchman took exception to Keane swinging a leg in his direction after winning a 50-50 challenge.
Never one to back down, he fronted up to the United midfielder and the pair had to be separated by teammates and the referee as Jaap Stam got involved on his colleague's behalf.
The pair are on good terms now, and have shared a studio on more than one occasion, but things were certainly very different when they were opponents on the pitch.
Alf Inge Haaland
Anyone who was following football at the time will be familiar with Keane's infamous foul on Haaland in the Manchester Derby, but the incident was unlikely to have happened without Haaland's own earlier actions.
During the 1997-98 season, when the Norwegian was at Leeds United, he responded to a challenge from Keane by standing over him as United's number 16 lay on the ground.
Haaland didn't know at the time that his opponent had suffered a cruciate ligament injury, and it is reasonable to conclude he would have been equally ready to front up to an uninjured Keane.
As we know now, that wasn't the end of the story, with Keane handing Haaland a serious injury years later, though the pundit has denied it was a premeditated move.
"My simple defence was, I'd played against Haaland three or four times between the games against Leeds, in 1997, when I injured my cruciate, and the game when I tackled him, in 2001," Keane wrote in his autobiography.
"I'd played against him earlier that season, and he'd had a go at Paul Scholes. If I'd been this madman out for revenge, why would I have waited years for the opportunity to injure him? I mightn't have got that chance."
