Pre-season is upon us with Premier League teams jetting off to far-flung destinations to tune up for the new football campaign.
The ideal for managers is for their players to boost fitness levels, find some form and for some youngsters to impress, with a few handsome wins thrown in.
But every once in a while, the definition of a 'friendly' goes clean out the window and things get a little bit nasty.
Keane orders club sandwich… gets beef
Arguably the most famous of all pre-season tour bust-ups came between Manchester United heavyweights Roy Keane and Peter Schmeichel in the corridor of a Hong Kong hotel.
Given both were big personalities, they frequently clashed both on the field and training ground, but things came to a head as United prepared for the 1997-98 campaign.
Having dispatched South China 1-0 to lift the Marlboro Cup, Keane and fellow midfielder Nicky Butt went out for a few drinks.
'We bumped into Peter at the hotel reception desk. It was about two in the morning,' Keane wrote in his second autobiography.
'We said a few words to one another, a bit of banter, a bit of stick. I went up to Nicky's room for some room service, had a sandwich, got up to go… Peter was waiting for me, outside the room.
'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.'
The scrap left Schmeichel with a black eye and Keane with a sore hand and, hilariously, the pair were put up together for a press conference once United arrived at their next destination.
'Nicky Butt had been filling me in on what had happened. Butty had refereed the fight. Anyway, Peter had grabbed me, I'd head-butted him, we'd been fighting for ages.
'At the press conference, Peter took his sunglasses off. He had a black eye. The questions came at him, "oh Peter, what happened to your eye?"
'He said, "I just got an elbow at training." And that was the end of it. The tour finished eight or nine days later and nobody said anything.'
Schmeichel has never given his version of events but Keane offered more hazy detail on the fight during The Overlap tour.
'I went back to Nicky Butt's room for a club sandwich. Really exciting stuff. No women or heroin, a club sandwich!'
The former United skipper also revealed that club icon Bobby Charlton had, at one point, poked his head around the door to see what the commotion was. 'I bet he was thinking f***ing hell!'
Unsurprisingly, when Alex Ferguson got wind of the punch-up he gave both the hairdryer treatment.
Thrown to the Wolves
Wolves' behind-closed-doors friendly against Spanish club Levante 12 months ago was anything but with four players sent off… all before half-time.
Perhaps the heat of Benidorm, where the Molineux club were on a training camp, led to tempers boiling over with a 22-man melee breaking out involving coaching staff.
That followed a series of rash tackles that very much went against the spirit of the occasion and while referees are loathe to brandish the red card in friendlies, Wolves' Yerson Mosquera and Levante's Enis Bardhi were given their marching orders.
Daniel Podence then got embroiled in a shoving match with another defender and a further two red cards were produced.
The officials threatened to abandon the game, now nine-versus-nine, if there was any further trouble.
But the beauty of friendlies is that you can do whatever you want, so both sides replenished to 11 vs 11 for the second-half.
The referee wasn't taking any chances, however, and ended the game after only 87 minutes of the 90!
Grealish's Mexican stand-off
Jack Grealish is well accustomed to getting tough treatment and comes out of many games with kicks and scuffs down his legs.
But the England star was up to his neck in trouble during Manchester City's pre-season tour match against Club America last year.
Grealish came to blows with Mexican goalkeeper Guillermo Ochoa after the 37-year-old stopper dragged him back to his feet after he went down in the box and didn't get a penalty.
Ochoa clearly believed Grealish was cheating and a shoving match ensued with nine Club America players rushing to get involved.
Things got even more heated later in the game when Grealish was hacked down by Bruno Valdez, leading to another flashpoint.
You wouldn't imagine City will be arranging another friendly against them anytime soon.
Richarlison quick to the punch
Brazilian star Richarlison had barely learned the names of his new Tottenham team-mates following his £60m move from Everton last year - but he was already prepared to fight for them.
During a pre-season match with Sevilla in South Korea, footage caught Richarlison appearing to aim a punch in the direction of Alejandro Gomez during a fracas.
It followed Gonzalo Montiel being left bloodied when he collided with Son Heung-min's inadvertent elbow.
However, another camera angle showed Richarlison was only acting in self-defence after Gomez swung first, before both players were held back.
Luckily for the referee all this happened on the stroke of half-time, the perfect amount of time for everyone to simmer down.
Hair-raising stuff for Guendouzi
Former Arsenal midfielder Matteo Guendouzi is certainly no shrinking violet and the word 'friendly' doesn't enter his lexicon.
So it proved when Guendouzi's Marseille took on Real Betis at the wholly unexpected venue of Chesterfield 12 months ago.
Betis had just snatched a late equaliser against the French club but instead of being able to celebrate, it all kicked off inside one of the penalty boxes.
First, Joaquin confronted Guendouzi and pushed his head into him before Andres Guardado tugged on his hair to light the blue touchpaper.
Not content with that, Joaquin aimed a dig at Guendouzi afterwards by posing in a wig on Instagram, writing: 'You make me hesitate to wear hair long.' Ouch.
